Is there a name for the position that Trinitarianism isn't necessarily wrong, but is theological speculation?

The term you are looking for might be "theological possibility" (at least that's a term used by Catholics about their own non-doctrinal beliefs).

Or:

41. Therefore, besides the theory of Limbo (which remains a possible theological opinion), there can be … .

— The Hope of Salvation for Infants Who Die Without Being Baptised

Or:

In writings before his election as Pope in 2005, the then Cardinal Joseph Ratzinger made it clear he believed the concept of limbo should be abandoned because it was “only a theological hypothesis” and “never a defined truth of faith”.

In the Divine Comedy, Dante placed virtuous pagans and great classical philosophers, including Plato and Socrates, in limbo. The Catholic Church’s official catechism, issued in 1992 after decades of work, dropped the mention of limbo.

— Catholic Church buries limbo after centuries | Reuters

Short answer

From the choices offered in this article and others, if you still truly believe in Jesus as your Lord and Savior, all these choices are NOT acceptable:

• Monotheism is too generic (might be mistaken for adherent of Islam / Judaism)
• Theism is even more so (too generic)
• Deism is too impersonal
• Agnostic Theism is too skeptical
• Fideism: faith divorced from reason

Better take your choice from a variety of non-trinitarian labels according to the one you are most convinced at that particular time: Adoptionism, Apollinarism, Arianism, Modalistic Monarchianism / Oneness Christology, Nestorianism, Sabellianism, Socinianism, Swedenborgian, Unitarianism, etc.

Coping with intellectual skepticism

I am offering this answer only as an aid to a willing Trinitarian Christian but who struggles intellectually to reconcile some academic difficulties with his / her faith. If there is at least a desire to trust IN a God who is potentially Trinitarian (with all the ethical and spiritual commitments that follow), then the cognitive doubt ABOUT this God can be categorized as "faith seeking understanding", which Christians across ages since St. Augustine have recognized, sympathized, and developed ways of coping.

Doubt about the Trinity is closely related to doubt of the incarnation of God as Jesus to save us (John 3:16, the famous verse), which is why the Trinitarian concept of God is so indispensable to Christianity. Rejecting this can bleed over to other areas of the faith. For example:

• If Jesus was not also fully God, how does he have the right to forgive sin, how does he have the power to save us and defeat Satan's attacks today and at the end of age?
• If Jesus was not fully human, how could he fulfill what Adam failed to do for us, how could he fulfill the Mosaic covenant for us, and how could he be a prototype of a human who received a resurrected body which we hope to have one day?
• If God only sent a messenger (ex. angel Michael) instead of His Son (who is Himself) how can God avoid the charge that He doesn't do what he preach: the ideal of self-sacrificial love?

Because this is so central, doubt about the Trinity is of a different order of magnitude compared to other doubts, for example doubting whether creation happened literally in six days. As long as we are certain that God created the universe ex nihilo (thus ensuring the belief that there is no God greater than the Christian God, and that God is outside creation) this doubt is relatively unimportant. But doubt about the Trinity needs to be resolved as soon as possible, as this can be seen as a critical illness of the cognitive aspect of our faith.

If you are this person, then you are a good candidate to receive benefit from this 2021 Christian Scholar's Review journal article by M. Elizabeth Lewis Hall, a Christian professor of Psychology at Rosemead School of Psychology at Biola University, an evangelical institution: Teaching Students to Doubt Well: The Roles of Intellectual Humility and Uncertainty Tolerance. Although the article uses the apparent conflict between science and faith as a sample application, I believe the same analysis and technique can be used for skepticism caused by trying to reconcile biblical data with Trinitarian concept. Thus,

• explicit knowledge = understanding and acceptance of Trinitarian theology (logical part of our reason)
• implicit knowledge = brain imprint of a soul who trusts in the Trinitarian God (faith + unconscious reason)

In the article she expounds on these topics:

• explicit knowledge (logical, linear, language-based, like subscribing to Nicene creed) vs. implicit knowledge (non-linear, emotional, sub-symbolic, image-based, largely outside of conscious awareness)
• how in the brain there is a priority of implicit system (emphasis mine):

  The brain sends information from its emotional centers that evaluate meaning and process our experiences (the implicit knowledge system) to the prefrontal cortex, the brain’s executive center (where we process explicit knowledge).¹⁸ Interestingly, the opposite is not true; the prefrontal cortex sends comparatively little input to the emotional centers of the brain. It is largely a one-way road. We are aware of our explicit knowledge system and we can direct it, but, by and large, we cannot direct the implicit knowledge system.

• how the non-biological portion of the cognitive structure for implicit knowledge is built primarily through relationships whereas explicit knowledge is built primarily through cultural forces (such as the Enlightenment conception of universe)
• dual nature of faith: propositional (explicit knowledge) and fidelity/commitment/trust (implicit knowledge)
• two kinds of doubt (cognitive dissonance or Enlightenment philosophy's "denigration of knowledge that is gained through implicit, affective, and relational means")
• two psychological dispositions/capacities:
  • intellectual humility: recognizing our cognitive limitation to make cognitive tensions (such as explicit doubting) less threatening, thus enabling us to reject the Enlightenment idea of autonomous rationality as counterproductive, but instead encouraging us to foster exploration of competing hypotheses. Example: how Internet makes one a lot more aware of competing belief systems.
  • uncertainty tolerance: using implicit knowledge to tolerate ambiguity (due to complexity, or indeterminate future events) which may manifest itself as negative psychological responses (cognitive, emotional, or behavioral). Example: worry from perceived discrepancy between religion and science.
• Pedagogical strategies for addressing doubt:
  • overcoming the automatic "one-way flow" between implicit and explicit systems by doing referential activity through a process of linking feelings and words in 3 phases: arousal ⟶ symbolizing ⟶ reorganization/reflection
  • through relationships: professors sharing to students how they cope with uncertainty through personal narratives rich with relationship with God, disciplinary integrity and intellectual humility
  • through images: becoming aware of our "pictures" / "social imaginary" / "worldview" which represent deeply held assumptions and unexamined beliefs associated with the emotional realm of intrinsic knowledge, and THEN the use of contrasting images so that our picture can be loosen from the associated feeling if the connection is not healthy
  • through narratives: exposing students to stories of scientists who have been successful at bringing together their faith and their science, as well as encouraging students to narrate their own struggles as a way to assist in their resolution

Conclusion

It is my fervent hope that aided by the journal article above, your journey to rediscover Trinitarian Christianity afresh can be fruitful, as one of many who has undergone successfully (for now, by the grace of God) the journey of faith seeking understanding.