But yeah, given how difficult it has been trying to accomodate comma users it is likely that C# Aurora will go back to being period-only until C# itself (or Windows) changes.
Yeah, for me this is already the case. I used to be able to use comma as a decimal separator in the mineral search window, but since 1. 9 I have had to use period in every window. It's a bit of a shame, since everything is so much faster with numpad and comma as decimal separator, but considering the (possible?) time investment to make it work, I'd much rather that Steve spent his time on something else. It's not that big of a deal to learn to use period instead.
As for the numpad: I have myself a , for it printed on my current physical keyboard on the numpad, but I use an English (US) keyboard layout (and others at other times), so the numpad works fine. If you do not need various keyboard layouts otherwise and don't want to switch the whole layout because other keys will then not do what they say on the label, it should be possible with very simple tools to create your own custom keyboard layout. I myself use two adapted for special tasks with a bunch of additional signs stuffed in. But for this, you can create one with just one or two keys changed from default, in this case just exchange comma with period, so that the numpad works for decimals. You can then use that custom layout in Windows while running Aurora by selecting it in the language bar (I'm not sure if it's displayed by default these days, but it's easy to find) in the taskbar just like any standard keyboard layout or add a shortcut for switching.
If you want to try it and can't find on your own, I could look up which tool I used, and if it still exists, give you a link. It may even be part of Windows, not sure. It really takes only a minute. Setup once, forget, use. My main one must be more than a decade old and has already been ported across Windows versions. It might only annoy you to have the language bar displayed permanently if you have no other use for it. But as long as you don't forget to switch back when you need to: it should be possible to setup a shortcut without it, I think.