Is there any way to get more Legendary Marks after all triumphs are complete?

Just a question for getting rolls of these old seasonal weapons in the future. The seasonal engrams at the monument in the tower have Something New, Mechabre, new Sixth Sense strand 120, and some other really good weapons that weren’t previously tiered. They only cost 2 legendary marks but the loot pool on some of the engrams is very large. I know we’re swimming in marks now, but they don’t appear to be unlimited unless I’m missing something? I also didn’t see a way to attune for specific weapons you want out of the seasonal engrams which puts us at the mercy of RNG.