The only times I have seen someone take issue was because of an ego-related response. I don't have time to deal with that in my day to day, so I generally just say "Whatever floats your boat" and fall in with their term, simmilar to how I would document code and fall in place with code style while working on someone's project with existing code.
Unless there is something I see that would actually cause real problems for future development, customers, or myself, I won't take issue with the little things. There are a lot of other hills that I would rather die on than spaces and hyphens.
Any of those should be acceptable. Your meaning will be understood. The rules of grammar have been relaxed greatly from what they were 50 years ago, especially with grammar "correction" software which wants to change my "I ate an apple." to "I ate and apple."
I would avoid frontend as it takes a bit longer to parse. It makes perfect sense to me for someone to write:
I am working on the front end of this process and need to hire some front-end developers.