.....You are right that by the time Mr. Collins propose, Charlotte didn't tell him what were her true feelings about him, but I'm taken this as a white lie, and probably Mr.C's pride would be hurt by this but I'm not sure how much or for how many time.
Mr. Collins was making a second offer in just two days time, and as much as we are told that he was no sensible, he must have notice the weird it was. For that reason I'm assuming he knew he was not in love with Charlotte, even if he said so on his proposal (because the situation demand it), and I'm also assuming (even with Fordyce's low ideas of women minds) he knew Charlotte was not very much in love with him, but she was taken the whole Mr.Collins package in consideration (a comfortable house now, with L.C. as neighbour, and a future security by the inheritance of Longbourne) as Elizabeth should have made.
As we are not told Charlotte exactly words acepting him, it's imposible to know how much she lied, but is true, she was deceiving Mr. Collins. But he just want a wife, and as soon as posible because Lady Catherine demand it, and Charlotte aceptance made him the happiest of man first because he went to Longbourn in a serch of a wife (mission accomplished) and second because he got his revenge from the Bennets, so I'm not so sure he would be very hurt at that moment, had he know all that was passing through Charlotte's mind; he was ready to accept Lizzy after she said no and explainded him why like 100 times ;-) it's not the same, but it gave us an idea of how much he wanted to go back to Hunsford and tell L.C. he was going to be married.
As for the "improvement" part: when I said I don't see Charlotte as a Mr. Bennet, not trying to improve her partner what I meant was that I don't see Charlotte making fun of his husband or not preventing him of doing something really really bad or stupid. If manage him is the only way she can find to do this I still call it "improvement" even if Mr.Collins is not aware.
I definitely don't mean Charlotte is going to dedicate her life to improve her husband, she has asked only for a confortable home and that's what she gets and for me she seems happy and I prefer to believe she will still think the same as years pass by.
Love this debate!