AAQ, why is my argument modernishe? You will know that in current parlance the word אירוסין means ‘engagement,’ but in Gemoro terms (and indeed in the Torah) it is a synonym for קידושין. Do we need here as well ‘a good source to claim that we can easily reject [the Gemoro’s definition of אירוסין] and inject new meaning into it?’
And if someone was to say that nowhere in Shas do we find any mention of getting engaged or of an engaged girl, would you refute him from the many times the term ארוסה appears there?
As for the Gemoro in קידושין, I don’t see anything for מפרשים to get excited about.