I just came by to say I’m sorry.
Can ‘appena’ really mean ‘just’ in the sense of explaining a reason, like “I only passed by to…”? I thought ‘appena’ with past tense like this gave a sense of an action immediately finished in the past (‘hardly’, ‘scarcely’).
Ciao @figgles and welcome - Appena = just, soon, as soon as, only, barely, hardly. So it’s a pretty handy word and in this context it can be just or only. (Nice that they came by to say sorry 
Hope this helps a bit… Ciao!
Does passata work if the subject is feminine?
Welcome and yes, you are right. With a female “io” “passata” does not only work, it is required because the auxiliary verb is “essere”.
Note that in Clozemaster the endings do not mtach the sex of the speakers.
A female voice might say " Io sono passato" and vice versa.
It is a well known problem, but it seems difficult to fix.