Latin personal names in Irish and Welsh

From: João Simões Lopes Filho
Message: 4913
Date: 2000-12-03

How are these Roman personal names in Welsh and (Old) Irish?
 
AURELIUS
AMBROSIUS
CONSTANTINUS
CAESAR
VALERIUS
VALERIANUS
CLAUDIUS
JULIUS
JULIA
MARCIUS
CAIUS    = Welsh Cei (Sir Kay) ?
 
 
Joao SL
Rio