They can usually help with anything on curved surfaces if it’s curved along one plane. Essentially the sticker itself is flat, so the transfer tape won’t hinder that, but it probably wouldn’t add much help with larger vinyl stickers, which you can usually handle as-is. Recessed stickers are a little more tricky, and probably better done with needle nose tweezers if small.
There’s a lot of fiddly text on these plant pots I made, placed along a curved surface, and pretty much exactly the kind of thing transfer tape works well with.
Oh, and Cricut machines are great. It’s my favourite ‘thing’. I recently upgraded from my 8-9 year old machine to a new one that cuts fabric as well as all the other materials and I love it.