First of all, as this appears to be your first post, welcome to the Musica Sacra forum. I hope you will find this both a cordial and informative place for the exchange of musical opinions and ideas.

There are others more qualified here than I, so please take these comments as those of an amateur and as nothing more than my own opinion. So ... typing off the cuff ...

I have always liked this piece of Chopin's, but would not have thought to recast this prelude to SATB. I think the general idea could work. I'm not sure if I would have arrived at the Kyrie for lyrics, but Chopin's prelude has a kind of mournful, bell-like quality that seems appropriate when asking for mercy. Naturally, it is well known as a piece for piano and organ. I wonder though if it might be a challenge for a choir to sing this without it tending to become dirge-like.

A couple things I noticed. The capitalization in the lyrics are not quite right. The 'k' of Kyrie should be capitalized, and the 'e' of eleison should not. Typically, I have seen the separation of the syllables for the Kyrie written "Ky-ri-e e-le-i-son" or "Ky-ri-e e-lei-son" if "lei" is alighted. (Also Chri-ste rather than Chris-te).

Finally, just a practical note. What can be sung depends a lot on who you have for singers. As a Baritone, the low F in the Bass is, for me, a stretch too far; for a real bass it is no problem. The high A-flat in the Tenor may be beyond the range of many tenors in a volunteer choir. For a professional, it is not. You might consider swapping the Alto and Tenor parts where you have the high A-flat, keeping the Tenor on the Ds while the alto has the A-flat-F#-G. I also noticed some tritone jumps (around measures 8 and 9, for example, where you have D-flat to G and A-flat to D). While these are not impossible, they could be a challenge for an amateur or volunteer choir.

Thanks for your helpful comments Drake!

I'm not a composer, but I've thought of setting this prelude, my favorite by Chopin, to a text before. So I cheerily endorse the effort.

I think this is a case of text/music mismatch, though. I think the music is going to work best with one- or two-syllable words, because three- and four-syllable words are hard to flow properly with this particular music. My vote would be to use "Lord, have mercy" instead or have a series of short phrases such as "Jesus, hear us," "Lord, forgive us," "Jesus, heal us," etc. instead and create a meditation piece out of it. (Admittedly, the latter is what I would want to do with the music, so you can take that with the appropriate grain of salt.)