Diffinity supports UTF-8.
Not yet quite as well integrated into the Windows Shell as WinMerge,
but it beats that on comparing non-Roman scripts such as Devanagari, Biblical Hebrew or modern Urdu.
Right alignment for the Right to Left scripts would be an improvement if they can manage that.
There's a user forum to report software bugs and/or suggest enhancements.
The developers are based in Sweden. Anders writes:
Best regards,This is a program we make on our spare time so time spent on the program goes up and down.