As the core of the Yibel Federation in various senses, the influence that establishing a Church by the Royal Court could bring would definitely be far greater than in any Duchy.
But why choose the Duchy of Lancshire?
Ultimately, even though the headquarters had begun relocating to the Yibel Federation, the "cute girl" of the Dinel Church, which had just been tricked by a scumbag, was now suffering from PTSD.
They were afraid that after entering the Yibel Federation, they had barely stabilized before they might encounter the same dilemma as in the previous country.
Therefore, lacking a sense of security, they preferred to give up that bit of potential influence and head to the place where their most trusted ally, "Kael," was, to acquire that insignificant sense of security.
Of course, even if Kael highly regarded his own influence, he wouldn't think it was simply for such a naive reason.