Using the game name instead of executable name is complicated, since ReShade won't necessarily be able to know the actual game name. Some games store this as the product name in the exe resources (the setup tool for example will try and display that while installing to a game when available), but most don't, so ReShade only has the exe file name to go by.
But I've added an option to include the preset name in the screenshot file name now:
github.com/crosire/reshade/commit/c6b1aa...93dfb4be643a1108634b