This needs to be examined feature by feature.
For example I feel pretty sure that it is a wrong choice to give a very long name "htmlspecialchars" to a function that should be used very often by people who mix their code with page design (most of PHP users). Abbreviating that to "html" would be an improvement.
Inconsistent function naming, such as "isset" but "is_null"; "strlen", "strpos" but "str_repeat", "str_strip" also does not provide an advantage. For the new language I would use one of those choices (but silently support the other one as a synonym, for former PHP users).
Abbreviating that to "html" would be an improvement.
Is that the only function that starts with "html"? Is "html" a common variable name?
Inconsistent function naming
I agree that this is a stupid design choice.
If it's worth saying, but not worth its own post, even in Discussion, it goes here.