diesel cell can't be used in diesel generator
methane and hydrogen cells can't be used in gas turbines
I guess that the recipes are missing?

Also it seems that currently nearly all recipes uses ic2 universal fluids cells, and in a lof of cases it's a mix of both, having normal cells as input and universal cells as output, as these cells are actually different thing and have different costs, this is a potential source of dupe.

Also using universal cells caused crafting recipes to be messed up like this one:
What it should be

What one can find while pressing U on a universal cell containing hydrogen

What I get by crafting

I'd suggest to use the old cell system instead of universal cells in all machine recipes to prevent such problems.