I'm seeing that the equipment gear (with Krastorio?) doesn't allow to be on a better aircraft cargo plane equipment gear grid. (I don't know whether to report it on krastorio mod or the better aircraft mod so I'm reporting in both modes.)

Sorry for the late reply - Didn't have email-notifications enabled[Enabled it now though], and haven't checked in a few months.

That's probably on my end.
I have not tested this. I downloaded Krastorio just now to look into their prototypes for the equipment grids.

Would this help? Unzip the BetterCargoPlanes mod and open the file shown in the photo and add this to it
https://i.imgur.com/EO6UUXJ.png
(If you don't know how to go there - type %appdata% in your Windows Search)

Me being an idiot accidentally filled in the bottom rectangle - that's supposed to be the same as the other 2, ie: "universal-equipment"

Don't mind this - accidentally pressed quote instead of Edit, and can't delete