As one might expect in a2000 document, Music in Catholic Worship and Liturgical Music Today, the 1972 and 1983 USCCB documents on music are cited. Before getting fussy about it, conservatives might want to consider the common sense guidance in these citations …
§ 88 § Music is integral to the liturgy. It unifies those gathered to worship, supports the song of the congregation, highlights significant parts of the liturgical action, and helps to set the tone for each celebration.(MCW 23; GIRM 103)
No problem here; the base reference is the universal document.
§ 89 § It is important to recognize that the building must support the music and song of the entire worshiping assembly. In addition, “some members of the community [have] special gifts [for] leading the [assembly in] musical praise and thanksgiving.”(LMT 63) The skills and talents of these pastoral musicians, choirs, and instrumentalists are especially valued by the Church. Because the roles of the choirs and cantors are exercised within the liturgical community, the space chosen for the musicians should clearly express that they are part of the assembly of worshipers.(GIRM 294; 312) In addition, cantors and song leaders need visual contact with the music director while they themselves are visible to the rest of the congregation.(MCW 33-38) Apart from the singing of the Responsorial Psalm, which normally occurs at the ambo, the stand for the cantor or song leader is distinct from the ambo, which is reserved for the proclamation of the word of God.
Locating musicians takes into account their first role, not as specialized providers, but as believing Christians who worship within a larger body. On the practical side, choir and instruments should be heard:
§ 90 § The directives concerning music found in the General Instruction of the Roman Missal and the guidance offered by Music in Catholic Worship and Liturgical Music Today (BLS 226-227) can assist the parish in planning appropriate space for musicians. The placement and prayerful decorum of the choir members can help the rest of the community to focus on the liturgical action taking place at the ambo, the altar, and the chair. The ministers of music are most appropriately located in a place where they can be part of the assembly and have the ability to be heard. Occasions or physical situations may necessitate that the choir be placed in or near the sanctuary. In such circumstances, the placement of the choir should never crowd or overshadow the other ministers in the sanctuary nor should it distract from the liturgical action.
All texts from Built of Living Stones are copyright © 2000, United States Conference of Catholic Bishops, Inc. All rights reserved. Used with permission.
Catholic Sensibility 
This is one place where I believe BOLS fell prey to the visual over aural dimensions of liturgy, and it issues involving the aural dimension of the Mass (as the ministry of musicians by nature involves), there needs to be much greater thought put into that dimension. I would say that the document should be revised in the future to seek to optimize the acoustical placement of the musicians, and to design new buildings with that in mind in such a way that their role as members of the faithful are also not unduly obscured. A shift in priorities, as it were.
Because it’s so easy to conceptualize visuals over aural matters, documents tend by their nature to focus on the former over the latter; it’s a cognitive blindspot that document writers in the future should strain to overcome.