Just posting this so others that may be looking for it can find a source of information.
Here's a short summary: For the last weeks and months I've been thinking about using 360ce (a controller emulator) so I can use my joystick and throttle in warframe (specifically for railjack). I know I know, there are better Space sims out there and so on, but I'm used to it and love using the setup I have whenever possible, so I wanted to try it. Since I already got in trouble once when DE gave me a suspension for having software that was considered to be breaking the EULA, I was anxious, since I didn't want to risk my account.
And yes, I tried other solutions, starting from Big picture mode in Steam, scouring the Forum an so on and so forth, all I could find was 4 threads where some people were obviosly using the software, at least a few years ago, still I was too afraid. Contacting Support and asking about this program specifically didn't yield and useful answers - only the generic warning about the use of third party software and such, not saying they weren't trying to be helpful, but the answer wasn't. I just hope if push comes to shove DE will recognize this and set me free.
So today, I finally decided to just risk it, and started Warframe with 360ce running, mapped my keys, and so far, it seems to be working and there's no ban. So it seems to be safe to use. It would be helpful if DE could add this program to a list of allowed programs that players can look up, but that's another topic in itself.
Tl,dr: Seems 360ce for mapping gamepad buttons to a joystick is safe to use at the moment, will update if stuff goes awry.