Robert You may find this interesting:
https://www.hcsjournal.org/ojs/index.php/hcs/article/download/123/112/216
This paper will give you a general idea why so little is available in English (mostly because very little is available in general).
Right now, it appears there are only few unpublished columns for PHerc. 26 (which is 'On Gods - Book 1') and fragments of PHerc 152/157 (Book 3) which you've already found on Twentiers' site (an excellent place to look for Epicurean texts).