Files using en:Template:PD-US-expired-abroad are not permitted to be transferred to Commons despite their copyright expiring and being marked as eligible for transfer.
Topic on Help talk:Extension:FileImporter
c:Template:PD-US-expired-abroad is not a valid license tag, it needs replacement anyway. You can change it e.g. {{PD-US-expired}}{{PD-old-70}}
before transfer, after which FileImporter will accept the file.
I'll concede to that. Thanks.