I learn something new every day. With paragraph styles you are correct, placing the tag at the beginning of the paragraph works fine (Word 2010). I have edited my earlier post to note that it was erroneous. Thank you.

I think for character styles you would still have to actually get the beginning and end of the text.

You're right about character styles; afaik, you need a selection to be able to apply them. I haven't experimented yet – it might be feasible to use a simple (i.e. recorded, not programmed) macro to apply them to a single tagged word, but I suspect that applying them to a tagged phrase would be trickier.