Greasy Fork is available in English.
Allows you to download subtitles from Netflix
< Rückmeldungen auf Netflix - subtitle downloader
I've never seen 1st one happen and 2nd one should be fixed in version 2.1.0. Just update the script.
i'm already using the new version
i checked it with firefox and both happening with
INSTALLED VERSION v2.1.0
v2.2.0 should fix 1st problem but as I said before v2.1.0 already fixes 2nd one. Try now.
2 problems
1. subtitles been downloaded as 'null' incorrect title name
2. sometimes subtitle is downloaded are damaged (mostly while trying download a season in one click)
here an example
http://s000.tinyupload.com/index.php?file_id=78023720335365675686