I checked my dictionary and I'm taking an educated guess here:
Perheps the book views Silona as a derivation from שִׁלַֹח (shiloakh). This is the name of a canal in Jerusalem. The name possibly derives from שֶׁלַח (shaelakh) "canal".
In different languages, the canal is called Siloah or Siloam. So perheps: Shiloakh - Siloam - (Siloan) - Silona
Though - even if my guessing is correct - that doesn't mean, that there is any etymological connection.
I found the name on a dutch website for names. It states no name bearers in the Netherlands an no meaning:
https://www.meertens.knaw.nl/nvb/naam/is/silona