Thats very interesting to see your strategies and thats not very easy to know which one was better.
I like yours because thats unlimited points with bishop.
Considering the gardens 5/3 seems to be honest. He was unlucky to have 3 on turn 5 but it doesnt matter considering the fact he had the last one. On turn 7 you could have taken garden for 4/4 but was it better than apprentice?
Did he make mistakes? thats very hard to say. Maybe i would have taken a beggar on turn 9 instead of tunnel. He needs absolutely to 3 piles ending to win, probably duchy-garden-coppers?
Things would have been different with that 4th beggar???
I agree with you, thinking about keeping loan more turns