Today's update seems to have had no effect, it's still chucking it down inside the train shed at Lime Street. It's dry at Huddersfield now though, except, correctly, for the centre strip which is unglazed. Maybe the game thinks the Lime Street canopy is unglazed as well.
Are you sure it's actually installed (if it's supposed to have done something and hasn't)? I didn't see any change from the BCC update, with the guards key still doing its four repeats every time, until I removed and reinstalled the DLC. Almost as though they'd forgotten to up the version number on the update and the system didn't realise it had to try to update it.
Noticed this today also after the update (PC Steam) still rains and snows through the lime stream station roof in SoS.
The PS4 said the update had been installed. When it obviously hadn't done what it was supposed to have done I closed TSW3 and restarted it. Same result. There's no way of removing and reinstalling just one route on the PS4 so I've no idea if that will fix it. It shouldn't be necessary, unless as you suggest, they've forgotten something.
Ahh, I'm on PS5 so it's a little simpler. With BCC, I never saw any change to the weird behaviour that the patch was supposed to fix until I removed and reinstalled the BCC DLC. Hopefully you won't need to do a full reinstall just to get the benefit of the patch - if it has notified you of the update (mine didn't), then I wouldn't expect it to need reinstalling.