[NoOne]

if format is bad, it may default back to a working version of the file. on second thought, just change one thing in the current import year and test to make sure it's not something simple first. then, .....

avoid the whole thing all together:
change the name of the orginal to OLD_era_stats.txt or whatever original extension is. move your edited one to the normal location. unless you have multiple leagues?

not an option?
keep trial and error with various options on that database settings page.

screenshot and submit a bugs report in that forum if you are certain it's setup correctly and somethign is amiss in application of your settings / choices.