I didn't read very far, but: Is this actively maintained? I really enjoyed Clipper and FoxPro back when, but would prefer sqlite or postgresql storage over .dbf files now. Wait, I see postgres mentioned in the README (off documents menu), but Harbour doesn't seem like an active project..? (More for curiosity than actual likely use, as I am working to learn & use Rust.)
The last date on the home page was 2016, but if you click "Commits" you see that work has been done this year.
Man, xBase was what launched my software dev career, loved it so much back in the day. But Windows really killed it--I know there were Windows versions of most (I co-wrote the first book on CA-Visual Objects)--but really MS Access, MS Visual Basic, and then Delphi really took all that market.
I did a lot with dBase II and dBase III back in the day; but it seems like the better option these days is SQLite combined with the application language of your choice.
For quick and dirty data-oriented projects, xBASE is wonderful, there's something clean and minimalistic about it. But I do prefer interpreted versions.