I installed the new version and at Gatwick (UK2000 EGKK) I get 3 options at most gates: BA, Virgin and Easjet - all incorrect.
You are again confusing the previous bug (which has been fixed) that resulted in random operators appearing in some cases, with how operators are being assigned, as a general strategy.
I really hope you don't believe that, for all 20.000 airports in FSX, we manually assigned the operators, one by one!
The GSX manual, and the PaintKit documentation both explains this. There's a SCORING system, with a hierarchical system based on the airport ICAO code, which assign operators in a very general way, in order not to have services coming from totally unrelated countries or regions.
This was refined with the help of website collecting informations about operators around the world, to give a bit more correct representation, but is still generic and, sometimes (a lot of times) they change, they go bankrupt, their contract expires, etc.
When we have better information, usually with the help of users knowing the airport, or if the operator website is helping indicating all the airports they operate on. Not all companies have such info, and some list an airport even if they only have an office there, without this being entirely obvious.
With previous GSX versions, you had to use the PaintKit documentation and edit a lot of SIM.CFG files manually, but now is no longer needed, since you can customize every parking or whole groups or terminals, or even the whole airport in one single step, overriding any strategy that might be used by GSX by defaul.