Because if it is, I didn't think we had "Part 1, 2 and 3" though they may be used to loosely describe those who have completed third and fifth years and their professional practice exams repectively. Maybe it has changed in the last couple of years, but I didn't think anyone had to have any post-third year work experience in order to complete 4th and 5th years, and if that remains the case your concern about the "Part 1" guy doesn't arise.
With regard to your boss's status, the RIAI website suggest that the assessment board hasn't actually convened yet so that for all you know he may have applied and until that application has been decided it is unlikely he is doing anything illegal by calling himself an architect. If he is actually doing that - you say only that he is practicing as one which will not be illegal even when registration is fully operational so long as he dosn't use the title "architect".
Insurance is obtainable without qualifications (incredibly) and his Opinions on Compliance etc should make his status clear. Whether they are acceptable or not is up to the recipient. But given your lack of regard for him, the most honourable thing you could do is resign from his employment and seek a job elsewhere. I wouldn't put this exchange on your CV!