In case any were wondering I was able to get Legends of Eisenwald to install and launch through Crossover. Haven't had time to test further but I will. Of course I would love a native version more but not sure of the devs plans. I was using version 1.31_(16810) of the game from GOG. My system specs:

AMD Ryzen 5 2600X | 16GB DDR4-3000 CL15 | MSI RX 580 8GB Gaming X | Mesa 18.1.6 | Solus 3.9999 | Kernel 4.18.5-90.current | Crossover 17.5.1