Everything is negotiable. Just keep in mind the brutal laws for owners if you stop paying and refuse to move out. It's literally years in the legal system. So you have to understand that. At one time at my peak, I owned 15 apartments in Buenos Aires. I sold off all but 2 of them. I would NEVER do long-term rentals with locals. When I did long-term rentals with companies they co-signed or with foreigners I collected typically 6 to 12 months ahead of time.
I think on the long-term rentals it's more competitive as a flood of properties went on the market once Milei fixed the rental law and many raised their prices. The economy is so bad that people just can't afford the asking prices so the market is slow. But on short-term rental market I am busier than ever. I own a place in Recoleta that I rented out on a 2 year long-term rental and one in Palermo Hollywood and my Palermo Hollywood is crazy busy. Renting it out about 25 days a month at around $90 USD per night blended rate. My friends that own higher end properties that are furnished well are also fairly busy.
But this is probably a good time to find a long-term lease apartment. It would be great if you can get that insurance as a foreigner. I'm not sure how expensive it is but I would say look at the cost. I generally find that as long as you're dealing with an ethical owner, paying several months ahead of time is not a big deal as long as you have a good rental contract.
You can save a lot of money going outside the traditional touristy areas of Palermo and Recoleta which I agree are the two nicest neighborhoods for living and very central but Buenos Aires has a lot of great neighborhoods. You can save a lot of money going off the beaten path and they are still wonderful for living. You can see a little summary of each neighborhood here:
Don't buy real estate in Buenos Aires without knowing all of the laws, ins and outs and all the possible pitfalls.
buysellba.com
Finding good architects are not always the easiest but I have done over 100 renovations as well as complete builds of luxury houses and had good people. I even used the same architect to build my house when I bought land in Punta del Este, Uruguay. There are good people out there. Feel free to DM me and I can give you a referral for good people.
Nordelta is a beautiful area but I'd say be careful as it's not really a liquid market. Less demand for property purchases out there so I know some people that bought really nice places and when they want to sell it's difficult. Just keep that in mind. Generally NO ONE is accepting low ball offers of 25% to 30% lower than ask. That just isn't happening in this market place. Demand has picked up.