Hi @Aklapper thanks!
For antispoof-noletters I assumed this was for the English MediaWiki and also the translated versions of the page AntiSpoof Documentation had the John Doe example and did not allow mixed scripts but antispoof-tooshort I had mentioned that listing the lower and upper limit of characters might be helpful and the above is just an example of how we could possibly phrase that. I guess there is some additional info on Account creation user experience/Usernames as that the maximum limit of characters is 40 but no lower limit (it seems it is 1 from the code) .

Note: Idea for potential format. Individual constraints on error messages that are too specific need to either be changed to the appropriate bounds or datatype's when someone here can direct me to some sort of deocumentation on what triggers the error messages to be generated else the error messages I have presented need to be less specific if no such documentation can be found.