I don't know where you set those options but the buffs alpha seems to be controlled by these 2 values
modules/oUF_AuraWatch.lua#L250 missingAlpha and presentAlpha respectively with defaults of fully opaque for present and 3/4 opaque for missing.
So if there's configuration entries for the AuraWatch module I'd look for those options there.
The author is active on Github - though not on this particular project which seems to be abandoned - so you might have better luck creating an
issue there.
It's possible they've stopped playing and have no interest in maintaining the project.