Yes but you can't really say CUP works with 4.13 until you have tried everything in CUP, which is a massive undertaking.
Look at CUP at the moment under 4.12. Despite the best intentions and great effort put in by Monty and his team, there are still countless problems arising that need addressing just to get a 4.12 version working correctly. Who has the wil to start over again for a 4.13 version of CUP.
I agree whole heartedly with mike, base game changes should have been backwards compatible, they aren't, which is massively detrimental to the game.
Personally I left upgrading to 4.12 until CUP came out. However my main interest is in night fighting, which 4.12 cannot handle well. So now I will have to make a fresh 4.10 install for night fighting, as this is the only version that supports the main must have night fighting mods, poltava has come to a similar conclusion with his DBW selection of mods.
This means though that any further mods related to 4.12 or 4.13 related to nightfighting probably will not work in my 4.10 install.
I'm not sure anymore if I can even be bothered to try and keep 2 installations up to date, the amount of housekeeping far outweighs any actual playing time. I even fear for me the days of il-2 could be numbered due to insurmountable amount of hurdles put in our way to get a game we would like.
Starting to think my spare time has better uses than updating and housekeeping a game for which the goal posts move every few months.