You will have a BIG problem then.
If you highlight/move the user to the "error" field, the "messages" (error, warning, information) section of the form will not be visible.....so how will they know the issue?
If you don't "move" them but simply "highlight" your error field (which I believe you can do in "field list" of the message handler) then it will kinda be up to them to figure out what error relates to what field(s)....and as errors tend to "cascade" in HCM P&F, this can get confusing.
Good luck with it though and report back on how/what you do!