In cases where any word precedes the subject of the sentence, the verb is inverted so that it follows the Dutch rule that the verb is always the second part of a sentence.
For example, "Echter ze kent daar niemand" is NOT acceptable because the verb is the third word in the sentence, not the second. So you have to invert the verb so that it is the second word in the sentence. Thus, "Echter kent ze daar niemand"
The only case where the same meaning could be conveyed, with the same words, in normal order, is if you START with the subject and put echter later in the sentence:
"Ze kent echter daar niemand"
I must confess I don't understand "echter" or "hoewel". "However" is a really tricky word in English, so I understand if it's just as confusing in Dutch.
I was tought in school never to begin a sentence with "however" (or "but" or "and"); that this was sub-standard writing acceptable only in advertising. So I wrote the translation as "I, however, do not sleep."
Be that as it may, I've only ever used "hoewel" in Dutch, and actually tried to construct my sentences to avoid using any type of "however". The word "echter" rather throws me because of its likeness to "echt", creating a subconscious link and making me feel it should mean "really".
I guess I'll have to create new mental links, and listen carefully for its use.