Roland already knew what Kaka had sent to cause his death.
His own derivative spell.
Roland didn't think it was his fault, and he didn't think that Kaka's death was in any way related to him. He didn't do anything wrong by giving something to a friend—what could be wrong with helping a friend? The only people at fault were the evildoers who were greedy and wanted to take other people's property or gain from their ruin.
He simply felt that it was his miscalculation for not considering that the headquarters' chairman would get greedy about this derivative magic.
After all, the Bard family was a big family in the capital. It was this notion that gave him the false impression that Kaka wouldn't suffer the same fate as Aldo, who had his achievements stolen from him. There should be a difference between people with and without a background.
But neither he nor Kaka had any idea that the Bards were being surrounded in those days.