The openvino stem separator fails to recognize the difference between acoustic nylon string guitar and a specific percussion sound which is a light rimshot, or stick sound, sort of a high pitched tap. It fails to separate that percussion sound from acoustic nylon string guitars. I contacted musehub about it, they passed the buck and said it’s audacity’s problem not theirs. The 16 stem separator did remove bass drum and shaker sound, but not a rim shot/stick sound.
OpenVino is not primarily a Muse/Audacity thing … OpenVINO - Wikipedia
You could try this ai vocal separation tool; it can separate guitar, piano, and other audio tracks, but I’m not sure if it will meet your needs. However, you can give it a try; it’s free.