familysearch.org: a large number of Gottschee records are available. The keyword to use to look at the catalog is Gottschee, Krain, Austria. This will get you to the resources. 

https://gottschee.org/
https://en.wikipedia.org/wiki/Gottschee
https://gottscheerhall.com/history
https://en.wikipedia.org/wiki/Mozelj
https://gottschee.org/history/
https://www.smithsonianmag.com/history/attempt-keep-dying-gottschee-culture-very-much-alive-180955915/  
This article mentions the 1919 demonstration:  https://gottscheeamericansongs.com/blog/  
http://www.gottschee.net/Dateien/Erlebnisberichte/Web%20Deutsch/J%20Tschinkel/TBRNM/05.html    

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From Donald Reindl <donald.reindl@guest.arnes.si>:

The Parish of Mozelj is part of the Diocese of Novo Mesto, but the parish's historical records are kept here in Ljubljana (by way of explanation, the Diocese of Novo Mesto only split off from the Archdiocese of Ljubljana in 2006). The records of births, baptisms, marriages, and deaths (including for your ancestors) are all held in this building in downtown Ljubljana:

https://goo.gl/maps/ZMnETKyCUxmHsbMb7

Their contact information is here:

http://www.nadskofija-ljubljana.si/nadskofija/nadskofijski-arhiv/

They suspended personal visits due to the Covid-19 epidemic, but I think they're still offering look-up services. Quite a few people at the Facebook genealogy pages for Slovenia and Gottschee have received material from them:

Slovenia: https://www.facebook.com/groups/183735961660531/

Gottschee: https://www.facebook.com/groups/26165327176/

Some of the Gottschee group members seem to have already collected a great deal of genealogical information and other records, so you may well be able to obtain some material directly from them.

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