[NTG-context] labeltext via lua

Hello, if I define a labeltext via \setuplabeltext[en][test=Something], how can I access that value via lua? (context.labeltext obviously prints the content, but doesn't allow me to use it in lua). As a related side-request: how can I fix expansion in cases like this: \startsectionlevel[title=\labeltext{test}] ... this causes the bookmark to read "test" instead of "Something". \expandafter\startsectionlevel... didn't cut it. Best regards Andreas