So for a while I have been trying to search for what samples Zwei and Saga use for their music, and after looking around and asking for help I have finally found out, It is the Korg M1, which was a synth that was used a lot during the late 80s to late 90s, here is a link to a video showing of the instruments, and you will notice right away that it sounds very similar: Korg M1 Synthesizer: Famous Sounds - YouTube
Do note that in the actual games the sounds are compressed, giving it that unique feeling. Some of these instruments are also used in Orta from what I can tell.
That is about it, I haven’t seen anyone mention the origin of these samples so I’m not sure if this is a new discovery or if this is already widely known.