Just my opinion here but feeder leagues are more of a means to an end than a way to play. They are not buggy, but they are often more trouble than they are worth since a mature 30+ team ML with 4 or more levels of minors requires so many feeder teams to fill a draft class. These feeders are real leagues, playing real games that slow performance of the game. The only use I've found for them is when playing "stats only" (ratings turned off) it makes it less of a guessing game since the draft class has a statistical history.
There are several on the OOTPB Mods page (link below). Most are a little older now but should still work. You may have to star them in older versions and import to OOTP18.
http://www.ootpmods.com//tiki-index....page_ref_id=78
My suggestion is make your own fictional baseball league. There are years and years of professional grade logos, caps, and uniforms on the mods page of this very forum. TX Ranger, eriqjaffe, Robo, Hockeyplaya, Cephasjames, & justafan (just to name a few) have made gigbytes of excellent quality logos & uniforms to make hundreds of fictional teams. Give those a look and start your own.