The .mdb files are simply Microsoft Access database files...and MS Access has a built-in spell checker. So one way to spell check them is to open the kitlog.mdb file from Access (you'll need a computer with MS Office installed). The file is usually found in the directory where kitlog pro is installed.
Once you open the .mdb file from Access, you'll see a list of about two dozen tables. Open work work_logs, click on the comments column to select it, and click the spell check icon. You can spell check other fields, like the picture captions, also. Be careful. If you mess up the other fields you probably won't be able to open it from kitlog pro again. Make a backup of kitlog.mdb first.
Since spell check is built-in to MS Access it would be trivial for the developer to add it to the GUI. Perhaps they will next version and charge $25 for it.