When to use the different words for to
Note that the original conlang author incorrectly uses at and bah when creating new words, compounding the confusion. Try to use the words correctly in other situations.
Never use either of these words in front of verbs. It is not necessary because that type of "to" is already included in the definition of the basic (infinitive, unconjugated) form of the verb.
at: to, toward
This is always a preposition, and it indicates movement in the direction of someplace else. Also use it between words (such as numbers or time words) to indicate a range. For example: Val slana at Keldabe. They go towards Keldabe.
bah: to (dative)
Use to indicate a recipient of an action (such as: dinuir bah [person], "to give to [person]") and other instances where movement is not involved.