Hi Gio. I feel your pain! I've not done much with components to date, and I've been having this issue (or at least something very similar) today while playing around with the experimental custom 'Event' property. Very frustrating, but I may have a solution for you. Here's the problem I was facing . . .
I'd created a custom Event property containing several colour parameters and called it, SetTheme. I initially chose Record as SetTheme's Return Data Type, because it would churn out a record containing the selected theme colours, e.g., MenuFill, DefaultTextColour, etc. This worked well in the component studio, where I was able to pass my colours into SetTheme from a gallery, and then use the output to format several controls elsewhere; however, when I tried to import the component into a canvas app I got the same error as you.
I fixed it by changing SetTheme's Return Data Type from Record to Text. Felt slightly wrong to do this, but the output still came out as a record variable, and it all worked perfectly.
Not sure I understand why Record didn't work, but this is an experimental feature, so that might have something to do with it. Or perhaps someone smarter than me may be able to explain?
So, double check that all your output properties have the correct Return Data Type and if you're using Record try using Text instead. (By the way, I'd also tried switching to a table and then referencing the first (and only) row – again, this worked fine in the component library, but I still couldn't import it elsewhere.)
One more thing to check . . . If like me you were trying to use an Event (or Action) custom property, make sure you have 'Enhanced component properties' switched on in your app's settings. You'll find it under Upcoming features > Experimental.
No idea if any of that contains the answer you're looking for, but I hope it helps! Good luck 👍
