It misses the security considerations for names. Almost nobody knows about nor implements that. Eg for filenames or variable names.
Magecart group uses homoglyph attacks to fool you into visiting malicious websites: https://www.zdnet.com/article/magecart-group-uses-homoglyph-...
Homoglyph attacks used in phishing campaign and Magecart attacks https://securityaffairs.co/wordpress/106916/hacking/homoglyp...
Forbidding mixed scripts fixes this attack. You also need to normalized names, and a few more minor things.