I wrote about Assire and other cards that interact with the opponent's graveyard since the open beta.
And without them the graveyard would have no counter at all, which would be a lot worse.
Xavier Lemmen is basically the only card that can counter the SK Beastmasters. Also, while being great against SK, he is a dead card against all other four factions and only 5 points for 7 provision without any synergy. And yes that makes him really binary. You likely win against a SK that heavily uses the graveyard, but you probably loose against every other faction. But he is a counter card so that is ok, because he won't be included in decks unless there is a graveyard overuse to counter.
I think making him a little bit less binary would be good, by making him banish up to 5 cards from the selected graveyard and boost by 1 for each, with 1 base power. That would allow SK players to still have ressing targets if they didn't overcommit, but would give him 1 more point in total.
I don't think Viper Witchers are that bad. As long as they aren't used with milling or the player doesn't use a hyper thin deck like Discard, there would be hardly any difference if the Viper Witchers player placed the card at the bottom. It is a 6 provision card with 4 power and the only synergy is the Witcher tag (Leo and Vesemir). Even with Emhyr into Vesemir they are still a low tempo play and without they are hardly worth it at all.
Also, there are as much counters for those two mentioned cards, as for Scorch. Once multiple set up units have been scorched there is no way to retrieve that game state even with ressurrecting units. This can be avoided by not setting up to many units with the same power (let's ignore Eithne here).
The same for VW and XL. VW require the player to not have too many high provision cards, while the rest are all low provision cards, but instead to have an equal distribution of provision costs, as well as not relying singlely on 1 unit to win the game. Then VW will only be a 4 point unit.
XL can be played around by not keeping all ressurrects until round three and not overcommiting to the graveyard. Also if the player has tools to kill his own units for a benefit he can still ressurrect his units.