At least for Germany I don't think refs start out better than they do in England, it's only been in the last 10 years that refs started improving before they were as poor as their English counterparts by and large. Think I mentioned it here but media pressure caused Germany's FA introducing some obligatory advanced training for top level refs, happened after Kießling's phantom goal in 2013 led to nationwide outrage.
Definitely more than clapping allowed at junior matches, depends on games and involved parents of course but you'll often find people shouting from next to the pitch. Honestly don't think it gets really bad though, when it does refs even interrupt the match to tell whoever to shut up.
Abuse from players can be more of a problem at games with notorious teams and/or derby matches, couple years ago a ref made headlines by getting knocked out by a player in a non-league match for instance. Reaction was that the player got sacked and the whole club had their season cancelled. Since then they often try preparing by choosing specific refs for those matches
This guy became somewhat of a mini celebrity for being a former bouncer, kickboxing world champion and ref for non league matches, would regularly ref critical matches heated rivalries etc. Gave loads of interviews about wanting to be a positive influence until he recently got arrested and convicted for being a pimp 😆