Unfortunately, the onscreen Keyboard for Desktop does not include all the symbols on the AltGr (Right Alt) layer. (The touch layout seems to be missing some symbols, but I haven’t looked into it closely.)
Thanks for the updated OSK. The tiny vowels are much clearer.
However, it seems that I misdiagnosed the original problem. The laptop with the problem seems have conflicting OSKs. When I click on the OSK button in Keyman, a different OSK appears, which does not show the correct layout (and it doesn’t have the Keyman header).
Regardless, it’s still nice to have a clearer OSK—those Hebrew vowels are tiny!