Will keeping n.ventrada 2 feet high harm it at all? Will it still flower without having a decent sized vine?
No, it won't harm the plant to continually trim the vines. It'll sprout off the sides of the vines, grow basal growths, and look bushy. However, I doubt you'd ever get flowers if you keep cutting down the vines, but ventrata is a reluctant flowerer anyway, tends not to flower even in perfect light on feet long vines.