But I hit a wall.First: Trying to find out what similar properties in the area (10 m radius) rent for, I used rentcast and rentometer for this, but they gave me two very different results.

I am a big believer in working with what the market offers you, instead of trying to grow oranges in the winter.Back in 2010 that was foreclosures, in 2015 it was short sales. 

If you listen to David Greene, he's hearing more and more stories about syndications struggling to keep up with their promises and a lot of investors are losing money, or pouring more money into the syndication to try and save their original money.

I've been doing some research on multi-family properties and trying to get a grasp on trends.

While real estate can feel overwhelming with all the strategies available, try to narrow down your focus early—like long-term rentals.

Trying to get market rates.

What are you trying to accomplish? 

Shop around with local lenders, ask these questions, and get answers before you try to buy the triplex. 

I'm currently researching the market, trying to get an understanding as to where these different areas are located in the cities.Any indication is welcome!

I don't think that is enough, but, the first thing is to go to your Banker and try to get qualified for a Loan.