I found the following differences to what is shown in the manual:
Right hemisphere breechblock control lights not working at all.
Ammo counters should show ammo of the four MG 151/20E only,
but ingame both inner counters show ammo of MG 131s.
The manual states that the firing button A (trigger in front of the sticks grip) should fire fuselage (MG 131) and wing root (MG 151/20E) guns and the B1 button should fire the wing guns (MG 151/20E).
Ingame A1 fires the MG 131 only and B1 fires all MG 151/20Es (which is somehow logical, but in in contradiction with the manual).
I attached a screenshot from the manual to clarify my point.
PS:
I have only access to an english translation of the german manual, you can find it by googling "Fw 190 A8 manual" or "D. (Luft) T. 2190 A-8". Has anyone access to an untranslated pdf of the original?