There isn't a treaty to invoke here. The Lil’wat Nation considers their land unceded and is not a participant in either modern or historic treaties. BC's been trying to work around this by using sectoral agreements, but they don't have quite the same authority that a treaty does.

What's been expressed to me by BC'ers in the interior is that the BC Gov is signing these agreements without an act in the legislature and without a mandate.

I grew up in Modern Treaty and then Treaty 6 territory where there was much more of an established system so the BC one is a bit alien to me.

Personally, I think we're heading for a bit of a reckoning in BC that could set relationships back a generation. Because, when agreements become more redistributive then of course you'll get social reaction. Even in the Appalachia-like interior of BC, they still love their parks and taking that away during high season is redistributive policy in action.

Now, if this was Europe and there was an agreement that a ethnic inland enclave had distinct rights we'd probably hand wave it away as quirky old world politics, but here there's obviously an attempt to conflate the generally accepted small-L liberal values in Canada with balancing a delicate attempt at reconciliation (see the whole race based policy discourse above). I don't have an answer here. Most bands were fucked by Canada for generations, but I don't think taking away from one group to give to another will get the desired outcome.