I believe the aforementioned writer has refuted extremely well, those questions that were relevant to what he wrote on. He was bombarded with many questions, many which were not relevant to what he had previously written.
To ignore or omit is not to accept a contrary notion.
Your question: “James insists that Christians must keep the OC Law, but Peter and Paul disagree. Please tell me the official RC church position on this conundrum. “
Your debate is not with the Catholic Church but with God. God’s Word does not contradict itself. Any attempt to do so should be reconsidered. There may be different audiences at different times, ad thus different things stressed. However, in totality, The Word of God stands as Truth.
Specifically regarding the Catholic Church and the issue you question :
CCC 121 “ The Old Testament is an indispensable part of Sacred Scripture. It’s books are divinely inspired and retain permanent value, for the Old Covenant has never been revoked “
The Old Covenant has been surpassed, but not revoked. The New is the source of all salvation even for those who adhere to the old. Jesus came to fulfill.
>>>God’s Word does not contradict itself.<<<
Thank you for making my argument for me. The epistle of James is not canonical.