Having discovered in the November 1907 edition of EPM that 18526 Carmen Carmila by someone named Robinson was to be dropped from the National Phonographic Company's Foreign Record Catalogue, I searched earlier editions in the hope of finding a reference to the number. Nothing was found in the 1904 editions (the year in which I suspected the recording to have been made), but the January 1905 edition contained this interesting article:
Firstly, of course, the list of recordings made shows numbers in the range of what I was searching for, even if 18526 itself was not shown; secondly the numbers in that range were performed by Señor R. Herrera Robinson, so I had a name match. I still had no confirmation of date of recording, however, nor even of date of release, but further searching brought be to the Edison Phonograph Monthly of June 1905.