It is for the Catholic Church to do so
No, it's for God to say.
He sent his Son. He initiated the Passover (which was the meal that Jesus was celebrating with his friends). He planned that we would be reconciled to him by the cross.
At what we call the Last Supper, Jesus was presiding, Jesus invited his friends, Jesus told them to remember him, Jesus was going to the cross Jesus told his disciples to preach the Gospel - they did and we follow Jesus today.
At the Eucharist we come to God' table by his invitation, to receive his Grace through his Spirit.
It's all from God.
It's not for any church to impose man-made rules or traditions which divide believers.
Well as you're a Catholic, you'd better follow them then.
I am not a Catholic and neither the Pope, nor the Catholic church, has any authority in my life.
The celebration is a real celebration and the bread and wine (or juice) is real bread and wine (or grape juice), but it is not the body and the blood of the Lord Jesus Christ.
Christ is present by his Spirit to all those who remember him, break bread and invite him into their lives.
Even if a person had no bread, no wine and no Priest, Christ would still be with them, and in them, by his Spirit.
Inconveniently God hasn't sent an angel down with a message to adjudicate any matter for around 2,000 years.
We don't need him to; we have the words of his Son.
He was sharing a Passover meal which celebrated the exodus from Egypt; that miraculous event where GOD rescued the Hebrew slaves from the Egyptians. Jesus said, "do this is memory of me" - from then onwards the Passover was to celebrate Jesus, who would lead us from slavery to sin and death and into life.
His blood was of the New Covenant and would be shed for the forgiveness of sin. His body would be broken for us on the cross. He - the Bread of Life - would give his life as a sacrifice for OUR sin.
Jesus did not say "believe in this way, use unleavened bread and real wine, don't use individual cups, make sure that each person who receives my body believes the right things".
Thank goodness I'm not a Catholic priest and won't need to explain to God why I prevented his children from honouring Jesus and receiving his grace.