again yoship stated several times there have zero interest in making any sort of hardcore content for a 4-man, more so as SHB got rid of optional dungeons as all of them are mandatory, and trusts probably arent tuned for anything too hard. There are several methods to go around this

1- Severe any affiliation with Roulettes
Sadly ppl dont run roulettes to think its usually for exp and tomes as such must be treated differently unless they got there own roulette
2- Turn them into 8-man
sadly 4-man content will never have anything hardcore unless yoship changes his mind, 8 man is easier for the healers and easier to balance and use more interesting mechanics
3-Make Gimmick runs
Niche as hell but to make the runs more interesting and have stuff like speed bonuses, Perfect runs where any invul turns to doom instead, Dare devil runs where if someone wipes they are booted from the instance similar to POTD, Invisible mode where the bosses dont telegraph attacks or some masochistic combination of the 3
4- Just make them more engaging
Not Matoyas relict savage but like general stuff, have different routes like a labyrinth style, take it easy on the gating to allow a level of discipline , add some layers to it like: DPS checks, mid trash pull mechanics, Mild Heal checks, Mobs with aggro resets, mobs that summon other mobs, Mobs with stunable raid wide damage, Mobs that Spawn in after a certain amount of time to layer out the tanks role, tethered mobs, Mobs with tank busters, Hazards like traps or aoe debris, elements that make the runs different each time like mobile mobs, Random spawns, possibilities are pretty vast and im shocked time and time again they dont do anything and stick to the most generic stuff. Bosses are usually fine just severly undertuned at times