Hi,
I'm used to this scenario. I've worked with Delphi 3 C/S and BDE/Paradox, back in the year 1999 - 2000, at Mercedes Benz (Middle East). We had similar problems. The problem is that you have reached 2 GB in size. The only option is to migrate to SQL Server or something similar, otherwise you will keep getting errors everyday !!!
There is no possibility to fix or tune anything in your scenario. You must migrate to a SQL Server database, especially considering that you have 15 simultaneous users accessing it.
If you want my assistance to migrate the project, I can do it for you, as I have done many migrations in the past - successfully ! Please see my Freelancer profile. Thank you.
Bests,
Steve