Nonlin, thank you for using Ninja! Addressing your issue on FGA import:
In the Manual, Page 22, the instruction is very specific: remove the first 24 characters of the CSV file header (the last character to be removed is a quotation mark "].) - like this: pls have a careful look at this screenshot: CSV-to-FGA-instruction1 hosted at ImgBB — ImgBB
If you remove less / more characters from the CSV header (not the defined 24), the file can not be recognized by UE, pls be careful! I have re-tested the method this morning under UE 4.25: works fine / no crash!
You could also watch this step-by-step tutorial video demonstrating the creation of FGA files: LINK
Have a go, and in case it still does not work, pls drop me a mail at andras dot ketzer at gmail dot com, and we could start debugging! Cheers, AK