The issue with the external keyboard should be fixed in the next Sailfish OS release:
[5.2.0.16] Hardware keyboard: keys 1 2 E S D F B produce no character in Android App Support (correct keycode, no Unicode mapping)
ISTR that the issue started with a Sailfish OS update, not with an update of the app. I could be wrong, though. What would be needed is a way to activate the keyboard manually. This would be a more generic fix than hunting for interoperability issues.
I tried you suggestion, but with “Typewise Keyboard” from Aurora Store and this also does not get activated.
So, I wait with the activation until the next Sailfish OS release is available and then I will connect the external keyboard again. (On my old Xperia I have also installed Android again, so I will install the banking apps there as fallback solution. My other Android device is a Gemini with hardware keyboard and I will probably sell this.)
Thanks, Dietmar