William in Spanish is Guillermo and Guillaume in French. Guillelmus seems to be a gaelic name, probably from Scotland.
I didn’t find anything specific so I give you below what I found hoping that it will help you, if not at the present, perhaps in the future.
Birth in my CD:
CODONI CODONI, Miguel Joseph Anton Christening
Birth Date: 26 Jul 1796
Christening Date: 28 Jul 1796
Recorded in: Santa Coloma de Farnes, Gerona, Spain
Father: Joan CODONI
Father's Father: Joan CODONI
Father's Mother: Rosa CODONI Y PALMAROLA
Mother: Rosa CODONI Y AIMAR
Mother's Father: Miguel AYMAR
Mother's Mother: Theresa AIMAR Y ESCABA
Source: FHL Film 1171787 Dates: 1763 - 1829
Death in Canada:https://familysearch.org/pal:/MM9.1.1/FLR1-HY9