Ils n'auraient jamais pu comprendre tes raisons

Clairvoyance? ;) No, seriously, you would need to know the context to distinguish. But there are such issues in every language:

It's a bear skin.
It's a bare skin.

Here is another ideosyncrazy of English. Try to wrap your head wround this grammatically perfectly correct sentence:

THE COMPLEX HOUSES MARRIED AND SINGLE SOLDIERS AND THEIR FAMILIES.

Solution: The complex (of buildings) houses soldiers (who are either married or single) along with their families.

You just gotta embrace it! ;)

-- Chris (not a native speaker).

And of course, in English "could" can sometimes signify an action that  you did habitually/ used to be able to do e.g. "When I was young, you could swim in the river safely". I guess this would trigger l’imparfait in French?