This is one hell of a can of surströmming you're opening here. I'm probably the last person on this forum to defend Bukele and his Chivo project but I don't think anything has failed, rather it has exactly gone as one could have expected.

Adoption, this is one tricky word, what does it even mean, people holding bitcoin spending it using for personal p2p transfers between family and friends or just trading? I can't picture an accurate definition of this adoption when it comes to btc, and even if we go for usage alone, there are other problems, for example is loading a debit visa card with btc usage?

One can argue that people hoard coins, very much possible, if the numbers from Salvador as little as they are would be quantified to the claims of users in the world, there aren't enough addresses and tx to cover that. So I'm not sure that adoption has failed, rather I would call it a failure of replacing traditional payment methods.
As for one of those numbers, the Chivo app downloads, the decline makes sense, every app does so after launch, you install it once and that's it.

But one more thing, and this might be a clear evidence of how things are going, is it just my impression or has Bukele stopped buying the dip for quite a while lately?