I have no problems with differing Christian faiths and their liturgy. It’s like “why” to me ... He did it all and there’s no need to add to His sacrifice for us. When He said “It is finished” He was talking about the Law. The Law is no more. He laid out the only thing we had to do and that was: Love G-d with all you heart all your soul and your neighbor as yourself. On this hangs all the Law. That’s it. One thing. Period. Nothing else.
Plus obey the 10 Commandments as well as the 2 Great Commandments as well.
I also view the next to the last Final Words of Jesus, “It is Finished” to also mean that His laying down of the foundation for the new covenant to be done.
What I see by the covering of the statues, icons, etc., as well as not using music istruments during the Easter Tridiumm from the end of the Gloria on Holy Thursday to the begining of the Gloria on Holy Saturday simply as a reminder not only to REMEMBER and NEVER FORGET what Jesus did on the Cross for love of our souls, but as a reminder of the reality that first followers of Jesus were by today’s standards traditional Jews who simply mourned for Our Lord during those three days.