Sorry, ran out of time before leaving for church.
What I mean is that sufficient time and lack of exposure, the common man probably wouldn't recognize Arrghoun words as Proto-Gvegh in the same way that many Latin Roots no longer have close association with their modern uses. Some have become half the meaning set they once were, due to borrowed words taking the other half of the meaning, some words being differentially dropped in different dialects and thus being broadened out to cover the losses (and perhaps even becoming the missing word's original meaning due to replacement by a borrowed word), pronunciation shifts, writing shifts, and other such oddities.
Plus, if talking an inscription, orthographic shifts. The attached image includes two forms of Latin Cursive... the lower one might very well throw even some latin speakers, and its' not even 1300 years out of use.
Orthography changes independently of meaning, its own slow morph.
The Cursiva Nueva has a few that would throw people; the cursiva antigua is 1700 years out of use, and they look like two different alphabets. But mind: in the last 1100 years, Slavic languages mostly went from Glagolitic to Cyrilic; the two are totally different baselines for character shape, but the same frequency sets,
Couple changes in meaning with a change in orthography, and it may be perfectly intelligible to the few scholars who can still read it... much like Demiotic was. Many Egyptian Copts can understand spoken demiotic inscriptions, but cannot read Demotic script. Again, about 1700 years. A Coptic alphabet based upon Greek replaced Demotic. And note that much modern Egyptian is actually Arabic; only a small minority still uses Coptic, and that for religious purposes.
http://www.omniglot.com/writing/egyptian_demotic.htm
http://www.omniglot.com/writing/coptic.htm
Couple profound drift (highly likely with Vargr) with orthographic transformation, and it may be utterly incomprehensible as an inscription.