Well... sometimes a small piece of software like this just falls right into place!
Got stuck with an old external disk formatted on NTFS (figured out that was the actual problem just recently), could only read from the device not write. Mac OS High Sierra and seemingly exactly what to expect.
Tested this Paragon solution and it worked beautifully, now I reorganized all backups and it works perfectly transparent and also surprisingly fast with this old USB (2.0) 500 GB drive. Works like any drive, no problems whatsoever.
Then I got the idea, why not try to revive an old 64 GB microSD drive formatted with ExFAT on an old Windows phone. No way in hell I could get it to mount on whatever computer mac or windows. Would not even format in Windows, discarded, same with repair options that failed.
So I gave it a try with the "verify" option (yes it showed up in the Paragon application), it worked for a couple of minutes and said the volume needed to be repaired (detailed info was provided about the reasons, omitted here). I clicked the repair button and Voila! A few minutes later the old hopelessly defect microSD drive not only worked just fine but also with the original contents intact.
Maybe this is not the right place for appreciation but I have to express my gratitude somewhere... great work and also unexpected value! Of course you could put a tad more effort in informing the user what is going on and expected time to complete certain processes but personally I just laid back and let it do its thing.