Installed and configured a Hebrew wiki using $conf['lang'] = 'he', which works fine with UTF-8. However, when using a template (e.g. 'default'), Hebrew diacritics (Nikkud) are rendered incorrectly: instead of being rendered within / around letters they occupy whole character spaces and rendered left-to-right to the right of the letter with which they are associated. Consequently, the resulting line of text exceeds the right margin. When no template is used the diacritics are rendered fine. Page encoding in both cases is the same (UTF-8). Using Firefox version 188.8.131.52 on Gentoo Linux.
Attached is an image of the good and bad rendered text (note the word to the right of the English word 'BLISS'). Also attaching the source text of this page (data/pages/start.txt).