You can import from one .fmp12 file to another on FMGo itself, or you can import from a remote hosted .fmp12 source as well. I always try to make sure that the local file I am importing from is closed via a close file script step before I start importing to the target file.
Filemaker Go does have a memory limit that can cause memory-heavy script actions to crash. I ran into this with large sets of data when testing FMEasySync (note that does not use import actions). Not sure if you ran into that here.
What's your goal of importing? Is there some other way to meet your goal?