So I am running a us new 3ds xl on 9.0 sysnand with 9.5 emunand and I have installed tri force heroes as a CIA and I want to play with my bro through download play since he doesn't have it but his new 3ds is up to date on system updates. When I first try to do download play the game was trying to download for over 5 min. Do both systems really need to be on the same firmware to work, or does it just take forever to download or is there some sort of workaround I can do?
If you use a different region game to your console it will give you problems in online and download play. I think the game has to be the same region as the other console but not sure (e.g. A Eur console running a U.S. version game, download-playing with a U.S. version console). To minimise problems you should get all consoles and the game to be the same region.
Although this may not be the problem, I was on a EUR console playing a U.S. version cia, and when I tried to download play with another Eur console, I got the user agreement coming up in a loop. Rather than failing to download which is what yours is doing.
And also you can't play local multiplayer with only two people, you have to have three. It sucks.