In Russian, any order is okay. You're right that the usual order would be the object after the verb, and it sounds more "right" to say it that way, but this order is grammatically correct too.
In English, it's quite subtle. 'More or less' is inexact, whereas 'somewhat' implies 'to a certain [ie. defined] extent'. But the difference is quite subjective and varies by context. As for equivalent Russian words/expressions I have no idea.
Is "Я его более-менее понимаю." correct? Это means this. Why isn't this translated: I understand this, more or less?
Его can also mean "it" in the accusative/genitive if it is substituting a named masculine object. Ты понимаешь русский язык? Да, я его понимаю.