Hi,
Can I make a multilingual sppagebuilder site
Yes, of course. Many websites made by our users have more than two lanaguages. We use Joomla core multilingual feature, so you don't have to install any extra plugin.
editing from frontsite
The basic langauge settings you have to do first from Joomla Admin. This is basic & common step for all users, components and sites. Then yes, new pages you can add and edit using SPPB front-end editor. SP Page Builder and his front-end editor allows you to choose language for each page and as I remember add that new page to menu.
Start from: https://www.joomshaper.com/documentation/helix-framework/helix-ultimate-2/multilingual-site