It's extremely rare to revisit a game like this for fear of new regressions. I'm sure every game goes out the door with 10-20 bad bugs that would be easy to fix, but it's just too late to touch. It also sounds like the fixed a lot of art/ambience regressions introduced by newer source engines over the years. Anyway, it's exciting to see an update like this, and a testament to their prior engineering that they can tur…
Regressions do happen which is why they opened a (public) bug tracker at the time, which is still in use: https://github.com/ValveSoftware/Source-1-Games/issues
If you have any HL2 issues, now is probably a good time to get them fixed before the developers responsible for the update get bored and move to another project.