If the sainted Calvin was God’s instrument in reforming the Church, then why has it been constantly reformed ever since?
“It is the will of our Master that his gospel be preached. Let us obey his command, and follow whithersoever he calls.” Not Saint Paul?
“Our only duty is to wish for what is best, and beseech it of the Lord in prayer” which makes no sense since his theology is based upon predestination. Why would one beg the Lord to change His mind if one believes that everything is fixed throughout eternity?
The church is constantly being reformed, Mark. Not changed necessarily, but refined and ever-striving toward obedience to His word.
"Ecclesia reforma; semper reformanda."
Now and always until the end.
Why would one beg the Lord to change His mind
No one is "begging God to change His mind." That sentence makes no sense to a Bible-believing Christian.
Calvin's remark that "Our only duty is to wish for what is best, and beseech it of the Lord in prayer" acknowledges God's sovereignty in all things and man's need for prayer and his duty to conform to God's will, which, by the grace given to him by the Holy Spirit, he will accomplish.
Rome has so much wrong that it's not difficult to understand much of its practices are not "what is best."