Certain issues here.

20 minute for a connecting flight is very tight. KNOWING that delays do happen! If you had issued it on one ticket, then the airlines would be liable but that wouldn't have happened.

Tickets issued on awards need to be reissued. Even though it was a FINNAIR ticket by issued on AA document, AA has to reissue it UNLESS it says somewhere in the PNR that AY can reissue or accept the ticket as is.

Basically by you permitting yourself such a tight connection between flights, I'm afraid that no one can accept the blame but yourself.

Live and let learn. Take the miles back.