Every damn smart light skill has different syntax and there is no way to get the Alexa app to just fucking tell me what the syntax is. The "nui' (no user interface) approach is cute but really falls flat when trying to do complex tasks or mix brands of smart devices.
Also, it might be Google that does this more often so I won't blame Alexa necessarily, but a lot of times when I ask things to play my liked songs I end up getting a song called "my liked songs" to play. It hasn't happened in a while so however I am phrasing it must be correct now but it's not something I'm super consciously aware of.
I never dove into the skill API, but I'd imagine you're setting phrases up. Can LLMs really help there? Like asking Alexa general information, I could see how LLMs were helpful, but asking it to turn lights on, how would that help?