One thing to remember, Godox do reverse engineer the protocols, only Profoto has a access to Sony's proprietary protocol.
Yes i can see it underexpose at wider apertures, but if it does so consistently it should be easy enough to work with no ?
Second thing is that Sony had issues them self with easily fooled ttl metering, coming from Nikon to Sony (a900) it was clear Sony was way behind in terms of flash. (yes despite their Minolta heritage )
Now i understand TTL can be useful for some photographers, especially when it comes to speedlight or on camera flash for events and what not.
However, if you have to rely on TTL solely and can't make adjustments on the fly with exposure comp. then you have bigger issues than a ttl bug.
This is the thing with TTL it won't ever be perfect, especially when companies have to reverse engineer it.
Did you download the rawfiles and looked at the charts ?