What's the word for technical/scientific/official terms?

One adjective for this, although it applies to more than just those three words, is domain specific.

From "What is Domain Specific Vocabulary?" by Chris Drew:

Domain specific vocabulary is the language that is used primarily within one area of knowledge but not others.

Examples of areas or ‘domains’ of knowledge include: Chemistry, Mathematics, Literature, Medicine and History.

The domain-specific vocabulary used by people in chemistry might include ‘molar ratios’, ‘element’, ‘compound’ and ‘substance’. These words have specific meaning to chemists and may not be understood by outsiders.

Domain specific language is a marker of inclusion within a community of practice. People who are comfortable with the discourse of a particular domain and can converse using that language are able to have more detailed, nuanced and in-depth conversations than outsiders.

As such, the Mandela effect is a domain-specific term that relates to psychology.

To paraphrase the example sentence:

I was beginning to think I was experiencing the Mandela effect, which has a rather unimaginative domain-specific term; in common use, it is "false memory."

Not sure if "appellation" would humor your snobbery :)

How about accepted or consensus? From M-W:

accepted: generally approved or used

consensus: general agreement

Your example:

I was beginning to think I was experiencing the Mandela effect, which has a rather unimaginative accepted name: false memory.

I was beginning to think I was experiencing the Mandela effect, which has a rather unimaginative consensus name: false memory.

You can also convey what you mean by reorganizing the clause to simply say it:

I was beginning to think I was experiencing the Mandela effect, for which the field has a rather airless term: false memory.

I was beginning to think I was experiencing the Mandela effect, known in the field as the more pedestrian false memory.

I was beginning to think I was experiencing the Mandela effect, which the field—less engagingly—terms false memory.

As you can tell, I don't love unimaginative here. I'm sure the practitioners have plenty of imagination but would prefer to use straightforward terminology, whereas the layman would enjoy something more evocative.