While asking this question where I was asking about building a brand name and motto using Latin, I realized that my choice of name is incorrect.
If you want to go with lux astrum or something similar, I recommend caution. The form astrum as a plural genitive is prone to misinterpretation. Especially some who have studied Latin are likely to mock it as a grammatical error, as the short form of the first and second declension plural genitive ending is not that well known. If people read astrum as singular (as was my first thought), lux astrum does not make sense. Therefore I recommend changing it to lux astrorum ("light of stars") or lux astri ("light of star").
The question therefore becomes this: To avoid changing any material already created, is there an acceptable translation for the phrase Lux Astrum, that doesn't stretch too much - i.e. can actually be considered correct form by somebody with complete lack of project-relevant information?