We have no right to simply state words can be used interchangeably, especially when they have different meanings. It is not “cherry picking” to use them for what they mean.
“ekklēsia” is a called out assembly of people, and not necessarily a Christian one (Acts 19).
“basileia” is a kingdom. People are ruled in a kingdom and not simply called out.
The are different words with different meanings and their meanings should be used.
Jesus life, death and resurrection was for atonement, not to establish a worldly kingdom. Again remember John 18:36 “My kingdom is not of this world”.
If you take words and make them a “broader term not just from its literal meaning”, what you are doing is eisegesis, or applying your own meaning. If the Scripture is from the Lord, then we need to do exegesis, or read what the Lord said.
I want to follow the Lord with His terms and His definitions. I am not going to place myself above Him to declare what should be.
What translation are you using? It intrigues me that you seem to be varying as the Matthew 14:17 quote I only find “Do penance” in the Douay-Rheims Bible, whereas most use “repent”. There is a difference in meaning.
The Scripture is very consistent, from “In the beginning” to “Amen”. Jesus is our Lord, our Creator, and our redeemer. He stepped into His creation to atone for His elect. During His incarnation He lived a sinless life and did not partake in worldly kingdom issues, but demonstrate to us that that was not His call or ours, as seen in Matthew 23.
We remain still at the beginning. “ekklēsia” is an assembly and not an institution. You have not demonstrated otherwise.