I will add two small items to the dossier about OIr. “stars”, and then I will leave this topic.
1. Old Icelandic possibly furnishes a formal parallel to my suggested reconstruction PC *glāu̯on- “glower” < PIE *gʰl̥h3-u̯-on- or *gʰle/oh3-u̯-on-. Alvíssmál st. 16 contains the acc.sg. eygló “ever shining” as the word for the sun in the language of the giants. And its nom. eyglóa is also said to be a poetic word for the moon. Nom. -glóa, acc. -gló “shining, shiner” could be a feminine -ōn-stem of Old Icelandic (pers. comm. Robert Nedoma), which means that we would also find an n-stem extension on *gʰle/oh3-u̯- as second member of a compound in that language.
2. And finally something very speculative about a poetical phrase. In Blathmac’s Poems ll. 767-8 the poet says
is a lám ro·sert indib
in fidchill do chainrindib
“it is his hand that has strewn (arranged) in them ( = the heavens)
the board-game of beautiful stars”
If we strip away all the poetical add-ons and embellishments (such as the wonderful image of the starry sky as a board of fidchell, cf. dil.ie/22014), we are left with an abstract formula X STREWS/-ED STARS (in HEAVEN), or in OIr. sernaid/ro·sert rindu (i nnimib). Keeping in mind that rind seems to be a specifically Irish innovation for the inherited word for “star” < PIE *h2ster- (NIL 348-53), this phrase can be projected into PC as *sternati/stert sterās (en nemisibos). Although etymologically unrelated, the verb *sternati/stert and the object *sterās create the impression of a figura etymologica in Celtic. I wonder if this is more than just coincidence.
As for the comparison of the starry sky to a fidchell board, see the picture of the Viking-age Ballinderry (Westmeath) gaming board. It has holes for the pegs bored into it; if you hold it against a light, it creates the impression of a star-sprinkled firmament. Note also the parallel with the East-Asian go-board which can be seen as an allegory of the starry sky.