You need to choose a marker for this which isn’t used for anywhere else - the marker \qa is the way to go, I think. Then in custom.sty, you can specify a font for this marker:
\Marker qa
\Fontname Charis
(or whatever font you choose - several Unicode fonts have Hebrew characters included)
Now \qa is a paragraph marker. If you want to mark only the Hebrew character (and not the word “Alef”) in a different font, it’s probably best to define a custom character style, for example:
\Marker heb
\Endmarker *heb
\Name heb - Hebrew
\StyleType Character
\OccursUnder qa
\Fontname Charis
For more information on stylesheets, see “What styles can be specified in a stylesheet?” in PT help.
Paulus+Kieviet