Template submission rules questions

Hi Guys
Have naming convention rules changed in regards to submitting a template?

Reading the sentence below, does that mean I can use all lower case, dashes & underscores ( ie like in BEM) as long as its readable/understandable? Would be a welcome change if it was…

‘Designers can use their own naming conventions as long as they are descriptive of the element. Client-first approaches are allowed and recommended.’

Also wondered if there are any issues concerning the use of custom elements & custom properties as I cant find anything saying no… Just in case!

Hope I posted in the right place! Thanks