@Max
They devote considerable effort towards it, an entire Clan really.
But on a fundamental level most of Rokugan does not like hearing about the Shadowlands, they do not like hearing about goblins, ogres, trolls, and so on to the point where it's become a considerable faux pas to do so.
There are several reason for this, first and perhaps foremost, these things are terrifying. In Rokugan being afraid is a sin, and unsurprisingly it's the one sin no one particularly likes indulging in. (Desire now that one Samurai and Heimin indulge in happily)
Since it's not actually possible to defeat the Shadowlands truly or permanently, they do the next best thing, put it out of mind.
Secondly, the Crab and the Crane truly and deeply despise each other. The Yasuki family was once a Crane family that defected to the Crab where they found themselves more at home. The Crane being the masters of both court and art gradually shifted the culture against the Crab in general, while as a rule they'll admit that those things must be fought, they don't particularly want to give the Crab credit it for out.
Thirdly, the Crab are actually damn good at their jobs. Seeing the Taint or shadowland beasties outside of Crab lands. Was for hundreds of years a pretty big fucking deal because it happened so rarely. Usually associated with the Empire itself nearly falling or a bloodspeaker cult. So from the outside it looks like the Crab have a handle on it. Which leads into the last point.
The Crab never stop asking for stuff, never.
Imagine if your friend Bob kept bugging you for all your food and precious metals year after year to fight this monster. But year after year you give it and the monster is still there. That'd be annoying, but this year's been a bad year, you don't have as much to give. But Bob doesn't care, he'll still take whatever you can give. So you give him what you can, and for a wonder he seems to manage okay. Monster is still fought off no real problems happen. You might naturally think to yourself 'Does Bob really need all that stuff every year? I have bills of my own to pay' so next year is better but you say 'I think I can spare this much.' Bob says you have more and should give more. You point out that you've given him a lot for not a lot of progress on his part. He calls you a pansy ass bitch and stalks off. Whatever he's a jerk, but you do give what you promised, and he makes it work. So you were right to dial it back. Except next year he's an even bigger jerk to you.
This is essentially how most other Clans interacted with the Crab for much of their history.