Seeing Australia follows English military traditions, customs etc, my guess is, that because the word Welch is spelt that way, and seeing it is a ''Royal" Regiment, it would need royal consent/assent to change the spelling.
However, you would not change the spelling, as it would alter the history and traditions, the 23rd Regiment on the order of battle, not to mention the Regiments accoutrement's, battle honours, standards, etc.
Very nice display and good to see, should be more off it, well done Fusiliers.
