The first comma is just phrasing in the tune; it doesn't add to the sense. It may have been
'Salve Britanniae Regina gracilis, ..floreat nobilis
(God) save you, gracious Queen of Britain; may she flourish the noble...
Just for comparison, a completely different Latin version of the National Anthem is given at latinisedhymns.org.
And here, poems to the first Queen Elizabeth by philological.bham.ac
I. Silva nemusque virens, et flore fragrantior hortus
Flourishing wood and grove, and garden pretty fragrant wiht flower.
and this, which includes a lady from the poet's private life:
ELISA claro tota fulgis auRO
LImbos et oras. Proxime tuo SI
SAltem nitori, en aurea est ROSI NA.