Update:
I got the end date fixed, but because so much time had passed from when my residency was first granted, I couldn't get a copy from Migraciones's website. I'm going off of what my advisor told me that his contact in Migraciones told him.
I left the country by bus for travel before speaking with my advisor (stupid, yes I know) and was told by border patrol to pay a fine while in the other country. I did so, got a print out, and was given a 90 day tourist stamp when I came back to Argentina. Thankfully I was allowed to re-enter, even though no one asked to see if I paid the fine. I just used the tourist stamp to leave at Ezeiza since I could not get proof of my corrected residencia
God bless Argentina, if an Argentine had done what I did in my country (USA) they would have been put on the first plane out and banned for years! Lesson learned.