I know most Roman Catholics only hear a small part of Acts at Mass (16.4% for those attending Sundays and Major Feasts over a three yr period) so they may not be familiar with these accounts.
I've been in church services where the Word of God was preached, people were convicted, repented and followed Christ.
I know that for that is what happened to me.
To me an alter call is just that....preaching the word...inviting people to respond to the message and follow Christ.
We see that all through the New Testament.
I don't know how Roman Catholics offer people a chance to respond to the message, but that's how Christians do.
How complicated do you want evangalisim to be?
Did you forget?
Catholics don't do evangelism.
As far as how complicated they can make the simple gospel message, well, this is a start......
There were no altar calls until recent Evangelical Protestantism - since it is a Evangelical concept. Catholic calls for repentance (in the Bible, early Christian era, Medieval Christian era, modern times) use some of the same language but are not an appeal to easy belief nor Once Saved Always Saved nor anything else that Protestant.
As St. Paul himself demonstrated in his own words he knew he was saved, was being saved and would be saved. He did not believe in the “Once Saved Only Saved” concept that is at the bedrock of the “Altar Call” in Evangelical Protestantism. Hence, those who believe in OSAS are much more likely to put stock in Altar Calls as a standard practice.
Many Protestants are more than willing to state that “Altar Calls” are a recent invention. Example:
“The altar call, contrary to what many believe, is a recent phenomenon made popular by the early 1800’s preacher, Charles Finney. Finney asserted that men and woman could be persuaded into believing the gospel by simply creating the perfect storm. An appeal to the emotions, the right lighting and music, and voila…you had yourself a convert. OK, I may be taking it a little further than Finney expressed, but it is clear he intentionally appealed to the emotions, believing that men and women could will themselves into belief.” http://thefrontporch.org/2014/02/wheres-the-altar-call/
http://www.pastormattrichard.com/2012/07/did-you-know-that-altar-call-is-modern.html
You should learn your history.