Obviously not. The Crypto Gambling Foundation doesn't require that for third party games otherwise Stake wouldn't be listed there anymore. When you play those games at stake.com, it's very clear that these are not internal Stake games.
I don't see any kind of requirements for membership on the CGF website. BitDice dropped or was dropped from the foundation a year and a half ago for hosting non-pf third party games. See
https://bitcointalk.org/index.php?topic=2178857.msg52889340#msg52889340.
Thank you for the link but as I understand Bitdice hasn't been dropped from the Crypto Gambling Foundation for that, they withdrew themselves from it.
I can't say I really care about the CGF, but I do think Stake or the CGF should clarify its stance on third party games and explain how this situation is any different from BitDice. OneHash deserves the same scrutiny.
Yes you are right the CGF should certainly clarify its stance on the matter, but I didn't see Stake claiming anywhere they were offering provably fair games only.