SableCrow

You only really need to change your locale back if your running an application that sets its language from that setting, and those aren't really common.

It's fine to leave it.

Have you rebooted after changing that setting?

Just use the search box and search "region". Open the program that pops up and go into the "administrative" tab. The settings you want to change should be there. Alternatively find clock, language and region settings in the control panel and then go into regions.

Edit: I wasn't really clear before, it should not change your whole PCs language.

Yeah you do for most unofficial VN translations. It shouldn't break your computer, all your doing is changing the "Language for non-Unicode programs" option. It does affect some other things, but you can always change it back if you need to. It doesn't change the primary language of your PC or anything.

I recall a similar issue I had on my setup. Turns out my Antivirus was interfering. Try running the program as Admin, then try temporarily shutting off your AV and trying again.