Those are not format tags in the common sense; they’re HTML. If I’m not mistaken most strings that appear in the GUI could contain HTML (and would render it as such).
It’s not feasible to separate the data and the formatting. In the example you’ve posted, how would you go on about it? Have one entry for each line (that could appear out of context and could provoke translation errors)?
It gives translators the power (whether this is good or bad is up for discussion I guess) to style the text for their needs while keeping the implementation of i18n strings as simple as possible. I think a few HTML tags here and there are doable.
I’m afraid Stonehearth does not support UTF8 encoded locales yet.