You could say "Was he uneasy."

Did he seem restless? I hope this is helpful

well sort of but I would only use the first one, "restlessness" is used but is relatively uncommon I'd stick to restless. "Was he restless/is he restless" is just easier and uneasiness seems just too complicated a concept, "was he uneasy" is just simpler. One thing, with English is that we tend to keep the language simple, there are people who like to overcomplicate the language and they have a bunch of reasons to do so, but better communication is not always one of them. :-)