Good news: Total Commander 9.51 still the works fine on Linux Mint 19.3 under Wine 4.0.
Why Wine 4.0 and not 5.0?
Because LM 19.3 makes installing Wine 4.0 very easy, whereas the current WineHQ instruction on installing Wine 5.0 on LM19.3 / Ubuntu 18.04 LTS is a bit tricky, not really straight forward, in particular for Linux users, who are not too experienced, yet.
Why do I mention at all that Total Commander 9.51 works fine on Linux Mint 19.3 under Wine 4.0?
Because I have been using Total Commander on Ubuntu/LM under Wine for more than 10 years now. And because in the past there seemed to be more Total Commander users like me, running it under Wine on Linux. Got the impression, we are a dying species. Like the dinosaurs.
Enjoy the Easter Days.

Karl