In my experience of working with white churches who are interested in attracting (or retaining) black congregation members, one common solution is to play more gospel music. It is sort of an if-you-build-it-they-will-come approach. And the logic makes sense. Gospel music is an incredibly important element of most black churches- whether its old school, contemporary, or a mix of both. So, its possible that playing more gospel music will have a significant chance of encouraging black visitors to become black members.
I am absolutely supportive of churches making changes to worship services in order to make the service feel like home for those who traditionally have had to adapt and assimilate into the structure of white church. But I think there is a slight misunderstanding about the depth and meaning of these changes. If your church has committed to a formula for playing a certain number of Kirk Franklin, Yolanda Adams and William McDowell songs by repeating them as best you can from sheet music, you've taken a great first step, but its time to take the second.
The second step is to recognize the cultural nuances that make gospel music what it is. Gospel has a lot less to do with mimicking an artist; in fact, that might be a clear giveaway that you're not really playing gospel music. Gospel music is about freedom. It's about allowing the music to move you, to course through you, to feel it from your head to your toes. It's about allowing the lyrics to wash over you, to repeat them as often as necessary, to highlight different verses or even specific lines spontaneously. It's about movement- waving arms, clapping hands, stomping feet. It is freedom of expression, expression without judgment. It is remixing in the moment. It is never playing a song the same way twice but possibly singing it three times. It is an imperfect but elating partnership between worship leader, musicians and choir. Gospel music is not a "what" it is a "how".
Figure out the "how" and you might find that there is less of a need to meet a quota of gospel songs per month. The real question is, "Are people free here?" Do people feel free to explore and express the cultural nuances of their own worship style, or is it suggested they should just be happy that their music is being played at all?
I use gospel music as my primary example, because of my personal background, but if your church is interested in altering worship to represent the culture of Puerto Ricans, Koreans or First Nations, I believe the questions above still have merit.
1. Do you understand the nuances of cultural worship styles?
2. Do people feel free to worship without judgement?
Answer, "yes" to both of those questions, and you will have created a clear path for your church to enter into multicultural worship!
Just one more piece of advice for churches who are trying to diversify worship: it helps to genuinely fall in love with the culture! I imagine it can be overwhelming for churches to take on new worship styles, songs, potentially new instruments and vocalists. One way to make the transition a little less intimidating is to sincerely enjoy engaging, learning, and exploring the culture. Love gospel music and it will show, even if you don't sing one "traditional" gospel song- the nuances of singing gospel will begin to leak and your congregation will notice. Fall in love and you might find it impossible not to insert another culture into your standard worship!
Blessings on your music ministry!