It doesn’t sound like their sulphate correction was due to policy changes.

Do you know how this model went with this years predictions?

I do not, this is not my area of expertise. Cross integrations are ongoing, for example the model presented in https://acp.copernicus.org/articles/11/11707/2011/acp-11-117... (among others) was cross integrated for CESM2 by relatively recent contributions: https://gmd.copernicus.org/articles/15/8669/2022/ (the latter incidentally explains some of the challenges)