When using a language that doesn’t use normal western Arabic numerals (1 2 3 4 5 6), the lock screen clock stays in western Arabic numerals. For example, if my system uses eastern Arabic numerals (١ ٢ ٣ ٤ ٥), my lock screen won’t change. Additionally, on iOS
the lock screen clock can be set to use Eastern Arabic nunerals whilst the system is using western numerals.
TLDR: add Arabic numbers on the lock screen clock, and let English language users set Arabic numbers as their lock screen clock too