Check this out:
This second set of 3 Lamentations are straightforward continuo arrangements Zelenka wrote to accompany the plainchant melody common at the time.
Simple but serene. Quite effective how the ensemble vary their accompaniment. Král also sprinkles some ornamentation.
Here's a sample of the published edition from 1999 with an extensive introduction from Thomas Kohlhase https://www.carusmedia.com/ima…n/40/4076300/4076300x.pdf
Turns out it's quite an important work to help understand contemporary Dresden plainchant practice.
Kohlhase refers to a 1904 recording of Moreschi, famously the last castrato. Here it is on YT: https://www.youtube.com/watch?v=F6bdPCVwoMw