I was intrigued by Albert Ganado's findings on the grammatical error in the Main Guard inscription (Confirmat instead of the correct Confirmant).
He believes this mistake could have slipped in when the inscription was renewed in 1851- less a misreading by the scalpellino. He quotes some pre-1851 authors who transcribed the inscription with the proper grammar - Confirmant (June 16).
I am not so sure. Several authors who, independently of each other, copied and published the inscription before it was replaced in 1851 already have the word Confirmat.
I will only refer to Andrew Bigelow, Travels in Malta and Sicily, 1831, p. 265; A Letter from Glenluce by William Dover, printed for private distribution in 1836, and Thomas McGill, A Handbook or Guide for Strangers visiting Malta, 1839, p. 59.
I believe it is more likely that the authors mentioned by Dr Ganado, realising the grammatical howler in the original inscription, made that small correction to improve the text, rather than that a number of independent authors (like those quoted above) transcribed and published incorrectly a large inscription that was staring at them on the Main Guard.