Don't read it if it bores you, but it's the same topics as the Republic (in some cases, the same material) presented in a different manner. For example, flip back to Bk. VII of Rep. - the parable of the cave - are you sure this is a parable about the soul? If you read carefully Plato is saying that there are four basic types of knowledge, corresponding to four basic types of entities (ideas, shapes, objects, and appearances). So it's a psychology that's inseparable from an ontology or a cosmology.
Likewise there is a tradition in Western philosophy of analyzing explanations into four types: what (form), of what (matter), by what (means), for what (purpose). Plato pioneers this in the Timaeus; you can see the same underlying question, is he talking about knowledge, understanding, and reasoning (according to you that would be about the soul and acceptable, right?) or is he talking about physical laws and cosmic processes? Not only is the criterion you propose (I would suggest) not an apt one for dismissing these topics, but Timaeus is actually one of the few works where Plato is in a sense trying to answer the question of whether e.g. his theory of the forms is psychological or ontological — more precisely, how it could be both at the same time.
Plato (=his characters) says certain things that are nonsensical and false that modern scholars would never get wrong. Modern scholars also invariably say certain things that are nonsensical and false that Plato would never get wrong. If you can learn to sift through and ignore the one you can probably deal with the other. But I don't know if this can be treated cleanly as a difference between facts and values, or between what is empirically known and what is unfalsifiable.
The really big difference between Timaeus and Republic isn't that the one treats metaphysics and the other treats metaphysics, but that one is driven by the ignorance of Socrates' interlocutors (as contrived by Plato) and the other lays out bluntly a logical overall order of moving between different topics/concepts/questions.
A more important general issue that will be hard for you to understand for a long time: sometimes a false opinion is nonetheless motivated by an important intuition into the truth. Getting access to this intuition can be immensely powerful (far more important than understanding a superficially correct answer, or even being correct oneself). The problem is most people can't understand how this could be true unless philosophy is like poetry and being right doesn't matter so long as you're clever and "original". On the contrary, the truth is all that matters... but I can only explain this conundrum in metaphors to you at this stage.