The CPC line of computers are notorius for having some of the worst emulators.
MAME - Issues: accuracy, terrible support for the plus line.
RetroArch - Issues: accuracy, can't change disks, terrible support for the plus line
WinAPE - Issues: accuracy, automation, fullscreen resolutions from 2004
Arnold - Issues: automation, joystick support, fullscreen not working
And the list just goes on.. with emulators that isn't being maintained.
But i fucking found a version of Arnold made by a french forum user on CPC Wiki, that fixed all the issues of Arnold and released his own version back in 2020
AND IT IS ... really good.
He wanted to make an emulator that works "from his couch: as he stated on the forum, that means its made frontend friendly with mordern features and Arnold's already great accuracy.
You can get it here: https://www.cpcwiki.eu/forum/emulators/another-version-of-arnold-emulator/
I think http://www.emu-france.com/emulateurs/10-ordinateurs/97-amstrad-cpc-cpc/ has a compiled version if you scroll down.