Ok, a purple tint can be an indication that a device has been set to component input and you’re feeding it VGA input. A green tint is the reverse.
Your second pic might be the main problem though. If this screen is stable, not rolling either vertically or horizontally, then three side-by-side images indicates a 45kHz input to a 15kHz screen. Three horizontal sync circuitry is only fast enough to catch every third sync pulse at that rate. Two side-by-side images would be 31kHz.
You should follow Calamity’s guide to installing crt_emudriver to the letter, first making sure to find the right version of crt_emudriver for your OS and video card, and then the right guide because there are two.
I’m not sure if this is affecting the colours, but I would try to fix this first. The guy who makes the retrotek stuff is reputedly a bit crabby. I would suggest looking on the shmups hardware forums as there are lots more listed there, like Mike Chi’s unit, Lunxbot3000’s unit, or the J-rok, to get you started. I’ve never heard anything against the Jasnet one though, so I’d say get a single stable image up on the screen first, and the email whoever sold you the jasnet transcoder for tech support if you can’t get it to work.
To that end, what cable are you using, have you swapped some of the inputs around?