FWIW I generally find that the search bar does work, at least if I search from here https://therassolution.kleinschmidtgroup.com/the-ras-solution-forum/
I always thought that it didn’t work inside a specific forum, but even that seems to work now.
One thing that seems to produce an error is including a colon : in a search term – which would be quite common when searching for an error message that HEC-RAS has produced.