I'm already working on an article (possibly two) covering this topic for Jeff.
Keklas,
Excellent! I'll wait to read your article(s) in Jeff's 'zine then!

Some of the more 'popular' worlds may not be included, while the inclusion of some worlds may raise questions.
Pooh on questions. The system you've come up with would something used by a tiny fraction of the population and then only in very specific circumstances. It's quite literally below the normal level of resolution for the game, but it makes for an excellent "We're Not In Kansas Anymore" tidbit. Only active duty IISS and IISS vets may have even heard of the system let alone used it.
When geologists speak of the "New York Devonian clastic wedge", it doesn't stop the rest of us from speaking of the "Poconos". Hell, only a few in every hundred thousand of us have even heard of the "New York Devonian clastic wedge".
Your system can be a great example of a "technical terminology" or "specialized vocabulary" in the 57th Century. As Wiki neatly explains "Technical terminology evolves due to the need for experts in a field to communicate with precision and brevity, but often has the effect of excluding those who are unfamiliar with the particular specialized language of the group."
It's touches like those that make a setting sing to one's players.
Of course, it will be based on events IMTU, so much of it has little to do with canon.
The specific uses you put it to in YTU shouldn't stop the rest of us from using it in the OTU or are own TUs. We've damned few examples of a stellar cartography specialized vocabulary in canon, there's the ray system mentioned in one of the Library Data books, the system body naming procedure in LBB:6, and nothing else. Your system could be added to that.
Regards,
Bill