In general you should avoid using HTML markup in the translation files. Yes, there are cases where this is already done, but (AFAIK) only when the messages are only used in an HTML context. There are cases where messages are used elsewhere (like in email content) where the markup is not resolved.
The "perNewton" has been fixed, thanks. The "degree Kelvin", though, is lifted (like the rest of the eng units) directly from the BACnet spec. It honestly doesn't matter to me which is used. But, still, there is at least an obvious difference of opinion. If others want K, it will be made K.