MTL = Machine Translated. It means it uses a language AIs like google translate for example to translate the script. And as you know, google translate for sentences is often very jank, incoherent even.
Edited MTL, which was what the original fan translation was for this game, means that the script is manually edited after it is translated to make the script more coherent and are often proofread also, although the quality of the end result is dependent on whoever is translating it.
Most of the MTL avaliable are fan translations, although there are some devs who release "offcial english" versions with MTL slap onto it, and the result are obvious on the end product.
You can even do MTL by yourself if u have a rpgmaker game that you want to play. There are guides online and also somewhere in the F95zone forums where you can check it out if you want, so unedited MTLs are basically a no effort translation that is a pain to read, but having something is better then nothing i guess.
With the official translation out, it basically means the MTL version is kinda obsolete, since official releases also often have better formatting and text fonts in addition to a proper translation. So if you want to play the game, you can just ignore the MTL version and get the official one. Also the official one has uncensored CGs while the original and MTL one are censored.