If you need any help learning how to play Battle Heat or Tengai Makyo Karakuri Kakutoden, you can ask me. Most of the other games that require no Japanese knowledge whatsoever have become highly collectible, such as Chip Chan Kick, Zenki FX, and Zeroigar.

In terms of eroge content; the PC-FX version of Pia Carrot has a fan translation and I recommend seeking it out as currently it's the only complete fan translation on the PC-FX (although the group's working on Ah! Megami-Sama and Team Innocent, so it seems, so it may not be for long.). I actually originally got my PC-FX specifically to play this fan translation and ended up learning how to play Battle Heat while I struggled to get it to work.

You could probably also play Der Langrisser FX to some extent using the SFC Version's fan translation as a basis for guidance.