Well, in the eye of the law, especially British law having shell companies isn't a thing worth investigating. I can't remember any company taken to court for having shell companies. Shady and untrustworthy, sure, but as far as I know completely legal. UK has a lot of tax free haven, there must be a reason for it.
I still don't like CIG but if the lawsuit gets dismissed with prejudice then I don't think CIG will have to account for anyting legally. I still don't like the company but really I don't like the man and family in charge of it. Worst, even if the lawsuit went Crytek's way the Roberts would still have the fortune they've accumulated from the project, which is what I have a problem with.
I always understood the government didn't like people evading paying taxes, which is usually what shell companies are used for.
I doubt they will investigate without some reason of course, but if it was discovered and proven, then they could be in hot waters.