Earok did a tweak on the engine to attempt to make it more compatible to third party joystick adapters, here's the link for a new test version of the game:
https://www.mediafire.com/file/ipyh2eq2k0ji3zz/CastlevaniaAGA_attempt_joystick_f...
WHDL: https://www.mediafire.com/file/bcm95k21czua508/CastlevaniaAGA_WHDLoad.lha/file