It is totally fine. I have LabVIEW 8.6 English on Windows 7 Japanese OS. No cross-language problem for years. 🙂
LabVIEW is a ASCII based (non unicode) program. Any language codepage is superset of English ASCII codepage. So LabVIEW English always works fine on any language OS without having to change regional/locale settings.
The additional work is necessary when you install a foreign language LabVIEW (such as LabVIEW Japanese) into English OS. Then you must change regional/local settings, but your case is different.
That's my understanding. Please correct me if anybody else has a better way to put.
TailOfGon
Certified LabVIEW Architect 2013