I have it.

@MJO Here are the Sarum tropes, and the rest of the Kyriale, https://macsphere.mcmaster.ca/bitstream/11375/16331/6/SM-kyriale.pdf

The same author has others: tropes of the Sanctus, Agnus Dei etc. I find them really lovely for meditation, even if most aren't liturgically useful. I imagine you can sing the troped Kyrie's though? There are lots of vernacular versions that already include extra text.

Many thanks to Richard C. I bought the book the other day, and look forward to its arrival. Even if not used liturgically, these are wonderful pieces for ad libitum use (Fons bonitatis, and maybe another, appear in the Cantus Selecti) during the Mass.

couldn't use them liturgically

There's a little discussion at PrayTell on that subject. In the OF there are forms A (Confiteor & 6-fold Kyrie), B & C for the opening Penitential Act (you can read them at this object lesson in kerning). The 9 options given there for the troped form are called samples, which I suppose to mean "in these or similar words". It seems that responsive reading is envisioned, but it's not very clear that only the priest may say the invocations. Lutheran hymnals in fact include the Kyrie Fons bonitatis which pairs wonderfully with Bach's C-U iii fugettas.

The ad libitum invocations CatherineS describes are often casually termed "tropes", but I think it's a misnomer.

Whatever they are, they are expressly permitted by the rubrics in the Roman Missal (pp. 518-519). They may be invented, but the Missal gives some examples in an Appendix as models. The examples share this characteristic: they are about Christ, not us; so they are all addressed to Him, they focus on His actions and attributes, and they hardly mention us at all.

If I remember, though, the relative clause in the Latin is rendered as a comma splice in English.

Domine, qui ...
is almost invariably rendered
Lord, you.....

This is where (hold onto your hats!) I think that the rejected 1998 Sacramentary kinda got it right, calling the "troped Kyrie" the Litany of Praise, for indeed, that's what it is:

You were sent to heal the contrite of heart: Lord, have mercy.
You came to call sinners: Christ, have mercy.
You are seated at the right hand of the Father to intercede for us: Lord, have mercy.

is a lot closer to this (from the Gloria):

You take away the sins of the world, have mercy on us.
You take away the sins of the world, receive our prayer.
You are seated at the right hand of the Father, have mercy on us

than to this (Penitential Act B):

Have mercy on us, O Lord.
For we have sinned against you.
Show us, O Lord, your mercy.
And grant us your salvation.

let alone this:

I confess to almighty God...that I have sinned...through my fault, through my fault, through my most grievous fault...

I have never understood how Penitential Act, form C, could even be called such since it isn't an act of penitence, as forms A and B are. Since form C doesn't even mention that (i) we have sinned or that (ii) we are sorry for them, and, (iii) according to the rubrics shouldn't(!), I just don't see how it's possible that it could even be called a "Penitential Act", except from the legalistic standpoint that "The Missal calls it such, and so it must be".

Sorry, I'm rambling and ranting.

(Incidentally, the other thing I think that might have been a nice addition to a new Latin typical edition that the rejected 1998 Sacramentary had were proper versions of the proper (for lack of a better term) "Hanc igitur" and "Communicantes" for Eucharistic Prayers II, III, and IV for those days that have proper Hanc igitur and Communicantes prayers in the Roman Canon.)