Technically they have not fired any staff in Spain or the UK. They have told OSM they no longer require their crew services. Therefore the pilots and cabin crew are still employed but via OSM.
So if any action was to take place against a company, it would be with the pilot and cabin crews employer, which is OSM UK or OSM Spain, not Norwegian.
I know OSM UK are doing everything they can for their employees.
As for Sweden and Denmark, I have no idea on employment law over there so cannot comment.
wish all the crews all the best and hope the 4th of May brings good news.