Well, guys. Failure was imminent.

Let's go over what we found on Sunday when we went to look at the truck:
First up, the frame had been repaired for rust damage or cracking. I wasn't impressed with the welding, but it was good enough. I 100% planned on purchasing a frame reinforcement kit for the vehicle with our remaining budget (kit cost about 350 euro) and welding it in myself.
E-brake didn't work. Investigation revealed that the linkage inside the drum on the driver's side was completely missing. The passenger side's cable had simply become disconnected. I could have had one working parking break with about 5-minutes of effort.
Fuel line replaced with non-OEM line (it was some sort of clear line that was being used as fuel line and was held in place by zip ties). I planned on running a proper line from the tank to the engine, and again it wasn't a show stopper for me.
Brake pedal goes to floor with a decent amount of resistance: Probably a brake bleed is needed, worst case a master cylinder. This is when I started getting nervous, but was willing to go with it.
Brake lights don't work: Ok. Probably a switch that needs to be plugged in, or replaced. Not the worst thing, but Mrs. Hungary is going to have to follow me home so other cars don't hit me in traffic.
Front turn signals dont work. He explains that he just replaced the lense assemblies up front, and that the bulbs just need to be installed. I'm not believing that at all. Who replaces the lense assemblies and not the bulbs??? But he has the old lense assemblies, so I have access to the bulbs, housings, and wires.
Engine starts and runs fine, but has a small coolant leak at one of the hoses. I can fix this with a better hose clamp.
My OBD2 dongle claims to be connected to the ECU but isn't reading anything from it.... Multiple attempts are made with no change in the result. May be compatibility error. On the plus side, there is no check engine light on, but there is a drivetrain light that is flashing (this may be how it tells me it's in 4wd, but I'm not sure).
Test drive:
Truck drives. Shifter is a little sloppy. I'm in a field of wet grass driving in tight circles in both high and low range 4wd, and I'm not picking up any signs that 4wd is working.... Normally I expect a truck to slip slightly as the drivetrain binds, but I'm not getting that feeling at all. I figure it might be the terrain and try a few more times in tight circles with the same results.
On the drive back I have a chance to look into some transmission noise. I'm detecting the sound of a dry bearing in 1st through 3rd (the fastest I can go on this short dirt road). It's at this point I decide we're not going to buy the truck, but it's when we get back and find out that (contrary to the advert) the truck has no current registration and will need to be road tested that we run away screaming.
oh well. We had to start somewhere, right? The search continues!
Of note, donations are still coming in. We are now over $4000 for the purchase of Yaroslav's truck!