Replace base character, retaining combining characters

Question

I have a vocalized Hebrew text; most letters are followed by one or more combining characters. I would like to replace some of the base characters, leaving the combining characters intact. It seems the only way to search by base character alone is to use \Z, but when I include that in the search pattern, the combining characters are discarded in the substitution operation. Also searching for the base char followed by a range of combining chars \m\%ufb25[\u05b0-\u05bd]* doesn't seem to work.

Example

ﬥְמַֽעַן וְהֽוּא־ﬥָֽךְ כְּסֶֽגֶן בְּאֶרְאֶﬥֵּי־אֵשׁ

This text has three occurrences of wide lamed (U+FB25) which I'd like to replace with regular lamed (U+05DC). Each wide lamed is followed by different combining characters:

• <ﬥ‎> 64293, Hex fb25, Octal 175445 < ְ> 1456, Hex 05b0, Octal 2660
• <ﬥ‎> 64293, Hex fb25, Octal 175445 < ָ> 1464, ...5b8, Octal 2670 < ֽ> 1469, Hex 05bd, Octal 2675
• <ﬥ‎> 64293, Hex fb25, Octal 175445 < ֵ> 1461, ...5b5, Octal 2665 < ּ> 1468, Hex 05bc, Octal 2674

The ideal solution would yield the following with a single substitution:

לְמַֽעַן וְהֽוּא־לָֽךְ כְּסֶֽגֶן בְּאֶרְאֶלֵּי־אֵשׁ׃

Note: I avoided formatting as code blocks, because the difference between wide lamed and its regular counterpart isn't apparent when using a monospace font. (Also it isn't really code, in the conventional sense.)

Answer 1

This search pattern seems to work on your sample:

/\%ufb25\ze\(\%u05b0\|\%u05b8\|\%u05b5\)*\(\%u05bd\|\%u05bc\)*

That pattern will match every instance of U+fb25, optionally followed by U+05b0, U+05b8, or U+05b5, optionally followed by U+05bd or U+05bc. Only what precedes \ze is matched so the replacement only affects U+fb25, preserving the combining characters.

For the substitution part:

:s//\=nr2char(1500)/g

or simply:

:s//ל/g