I don't know all the ins and outs of gate assignments, especially with add-on airport scenery. So, why is there this discrepancy with the "real world gate" and fsdt's KLAX gate? Is there a way to fix this or remap the gate assignments?
You are assuming that, because you found a difference in one of the parking spots at TBIT, the parking assignment at FSDT KLAX are not accurate in general,
Instead there's a specific issue with just TBIT: when the scenery was designed and released ( KLAX has been released in 2011 ) the updated TBIT terminal wasn't even built. There was only a provisional official chart, but no definitive parking number assignments, but we released the scenery that way, thinking it was better to have TBIT in its final state, rather than having a construction site in the scenery.
This means, now that in 2014 parking spots are of course final, the scenery is not updated, but that's normal for basically all sceneries out there: they are usually updated to the date of their release, and in this case, it's not that you are missing any spots, everything is there, just not with its final number, and that's ONLY at TBIT, because the rest of the airport parkings are all accurate.
We might update the numbering with a future upgrade of the scenery.