It’s hard to find a 100% accurate resource. You have to sort of piece together lots of data points... TP, resort fan sites, experiences here, etc. Even then, things change. Plants grow or are cut down, Disney tweaks things, etc.
In my experience, if you could see the water, the Outer Building-Lagoon View room category would in all likelihood be the assigned room category for that room. That’s not a 100%/take it to the bank statement though.