Would it be possible for Cafe Tran to remove from the F4 list non-translatables once they are copied to the target segment without using the list, i.e. with ALT + I or copy and paste. That would make the F4 list clearer and reduce the possibility of making a mistake.
Each occurrence of a given non-translatable that is a proper name should be marked in the source segment and put on the F4 list in the order of appearance. Such solution often allows for correct insertion of non-translatables without having to check the numbering in the list and is very convenient.