I love challenges like this! I know what you mean, we're
Dutch, living in Germany with a child that goes to a Britsh school. So yeah, we're currently doing the Trilingual Challenge as well!
I hope these suggestions are helpful. Some might be slightly religious, but since they used so widely I'm not sure if it bothers you too much (you can always ignore them :P).
AbelHugoRogerBrunoMarcMarcoMarcelRobert /
Roberto (
Roberto is sufficiently recognizable internationally in order for it to work I think)
AlanAlbert /
AlbertoAlexisArtur /
ArthurBernard /
BernardoCasimirEdgarErnestHectorLambert /
LambertoOscarQuentinOrlandoMartinMateoElias /
ElíasFlorianJulian /
JuliánMilanNicolasFabian /
FabiánRoman /
RománRuben /
RubénGael /
GaëlRenéLuca