I suggest that you contact support, last I heard heard was no work-around, other than not having saved T2T imports and doing them a different way like with a Pipeline.
If I create a pipeline for the same automation and activate sandbox, will I get the same error message? Do you know?
Well, you won't get that error but the pipeline won't automatically copy so you will have to make pipelines over again from scratch or more likely you will export the pipeline to YANL format, and then there is an app in the exchange somewhere that helps you convert the YAML over to your new app.
But actually, I can't speak authoritatively about how pipelines work with an app in the sandbox.
