According to the 17+ announcement topic, it states that 17+ Experiences should still adhere to the Community Standards. Over there, it states that:
- Discrimination, Slurs, and Hate Speech topics are not allowed.
- Profanity is not allowed.
I assume that in Roblox’s “aging-up” programme, words like “lmao” will most likely be allowed, but as of now, as mentioned by @CKY_DRAGON , the level of swearing is not specified, so nobody’s sure of it at the moment.