Why do you need to bring the Targum Yonasan to prove that the Jews were not oleh l’regel at פסח מצרים? I mean, without the Targum Yonasan they simply stayed in Mitzrayim until the next morning, so they were certainly not עולה לרגל!
You then say that since בני ישראל were not עולה לרגל at פסח מצרים, no קרקע was required. I suppose you mean that even according to the Minchas Chinuch בדעת Tosafos that a regular קרבן פסח requires קרקע for it to be an obligation, פסח מצרים is somehow different, and does not need the ownership of קרקע for it to be a חיוב. So we agree that the כנענים could not have had a טענה regarding פסח מצרים, since there is no need to have קרקע for it to be a חיוב; and, if מעשה בראשית had been written after והגדת לבנך, they could not have had a טענה regarding any other פסח either! Which brings us back to your original קשיא (which is really the מעשי ה’s explanation of Rebbi Yitzchok’s קשיא): why could מעשה בראשית not have been written after והגדת לבנך?
So what have you answered exactly?