Some of the rhetoric we've been hearing lately deals with the overall attitude and alignment regarding a simple phrase: how we label the Church in this country. Many (including the editors and staff here at CNP) would be very wary of a label that comes close to yours ("America's Catholic Church"); similarly, people speak of an "American Catholic Church." We would argue that there is one Catholic Church in the world, many dioceses of which lie within the geographical confines of the U.S. There is not a separate or distinct American Catholic Church, or Canadian Catholic Church, or even Italian Catholic Church. Only one. Our preferred label (and that of the official Church) to describe the dioceses in America would be: The Catholic Church in the United States.
It's perhaps a nit-picky argument, but labels can be slanted and ideological — witness "anti-choice" or "pro-life," labeling the same group.
When viewed as the Catholic Church in America, we don't need to make huge efforts to "inculturate." We are first Roman Catholics, and only secondly celebrating Mass with some American customs and music. Realize that it would be entirely possible, given that the Novus Ordo can be celebrated completely in Latin, for a typical Ordinary Form Mass in the U.S. to be indistinguishable from a Mass in Canada, Ireland, Australia or the U.K. (apart from the local accents during the English readings and homily), particularly if the music was Gregorian chant.
In terms of guitar and piano accompaniments, we must realize that neither popularity nor widespread use makes a notion "correct" or even "appropriate." Guitar and piano (and I might add other instruments like clarinet ensembles and accordion bands and bagpipes) are not seen by the Vatican as being proper to the Roman Rite. On an even more basic note, certain musical styles are proper for certain milieus: Gregorian chant is not proper at a nightclub, a polka band is not proper at a high school graduation, Broadway styles are not proper in church.
These ideas about what is proper to the Roman Rite are not at all arbitrary — they're in Vatican documents, which unfortunately have often been summarily ignored by musicians and pastors who happen to disagree with them.
Use of Gregorian Chant
The church acknowledges Gregorian chant as specially suited to the Roman liturgy: therefore, other things being equal, it should be given pride of place in liturgical services [Constitution on the Sacred Liturgy par.116].
Use of the Pipe Organ
The pipe organ is to be held in high esteem, for it is the traditional musical instrument which adds a wonderful splendor to the Church's ceremonies and powerfully lifts up man's mind to God and to higher things [Constitution on the Sacred Liturgy par.120].
While the organ is considered suited to the Roman Rite, the "chorale" or "hymn" is not. The Church gives us what are called the Propers of the Mass for our use. These are texts for every celebration of the Church year for the Entrance, Offertory and Communion times. Associated with these texts is the music (Gregorian chant) that the Church links to them, found in official books like the Graduale Romanum and Graduale simplex. As an example, the Gregorian chant Introit, Ad te levavi ("I lift up my soul"), is given as the proper entrance music on the First Sunday of Advent. Any other music that we use is a substitution for this premier option. One can see how far afield we've come in the U.S. when the substitution (i.e. a "hymn" or "praise song") has become the norm — and all this with many pastors and certainly the largest part of the congregation not even knowing the situation.
I would suggest that if you really want to know what the Catholic Church teaches about music, that you read directly the pertinent documents from Rome:
Mr Penkala can be counted upon.