all that matters with a stickbow is the type of string fiber you use, *not* how the string is made - modern hmpe fiber *only* for bows that can handle the added stress, else use dacron.
for that matter, you wanna go "true trad", use bowyer's knots (timber hitches) for both string loops and then for sure you won't need to spin or twist up a string. Seriously.
i'm a huge fan and proponent of endless strings, have been since the late 50's. i've twisted my share of flemish, but endless is easier, faster and way more accurate in terms of string-to-string length consistency than flemish.
fwiw, in a few weeks i'll be posting a video on how i spin endless bowstrings.