As much as I know , wild ones are not bitter .I regularly see poors , particularly road and construction workers , picking it from wild vines . Occasional bitter ones , yes .
Cucurbits can be bitter occasionally , I know from experience . Our Indian Desi Cucumber is famous for bitterness , particularly on caudal end and sometimes whole . Luffa cylindrica , Luffa acutangula , Lagenaria vulgaris , Trichosanthes dioica , Kakdi ... bitter pieces are encountered time and again . In Coccinea grandis , what is grown is a selection and propagation of non-bitter variety year on year . When a farmer encounters bitter vine , he will simply uproot it .
Dinesh sir , in Gujarat it is called Giloda and Tindoda .
In Bihar , Kundari .
I left home in 85 . Till then Coccinea grandis was not introduced as vegetable , at least in my area (Siwan) and in Patna and Bhagalpur .But diabetics were known to gather it from wild vines and use it as vegetable . Interestingly , wild growth was known as Tirkol तिरकोल . By 95 it was an established vegetable in markets of Bihar . I came to Gujarat in 96 and it was already there .