Just a thought to the developer:
Renders look to be good enough for me to try this out if this was running on Renpy that this custom engine seems to idolize. Renpy is a free platform that supports all major operating systems with their wide variety of regional settings. Because native Windows users seem to have difficulties, I'm not going to even attempt to run this on Wine in my daily driver that is Manjaro Linux. (My former bootable Win10 installation is a virtual machine these days and I haven't booted it in months now.) If I was developing a visual novel and I liked how Renpy does things, I'd use Renpy instead of making my own engine that has issues running in native Windows environment.
Are you doing this visual novel A) to make as a good visual novel as you can or B) to test out your custom engine by making a VN? If the answer is yes to A, I'd stop using my custom engine and convert the VN into Renpy. If the answer is yes to B, you should tell everyone that this is actually a test case instead of a valid game because your attention is mainly on the engine instead of the visual novel. Currently you must be dividing your attention between the engine and the VN.