What settings do people use with Lyra cartridges?

Start with 100 Ohm. If you can get hold of variable resistance, than all you have to do is to move potentiometer till you find sweet spot, than measure your dialed resistance and affix the resistor of identified value.
Usually all you have to do is find load resistor for each channel and simply add(solder) ~100Ohm in parallel with existing 47kOhm one. If you'll have to experiment further than the relationship of total resistance in-parallel is derived with following relationship: 1/rt = 1/r1+1/r2... Therefore if r1 is very large compared to r2 than the total resistance is mostly defined by r2, the smallest resistor as current flows larger on smaller resistance.
The resulting resistance will be slightly smaller than 100Ohm, but would suffice for experiment.

If your preamp has stability problems, start with 100 ohms.

If your preamp does not have stability problems, you will be fine with the stock 47K. Loading has everything to do with the preamp and not so much to do with the cartridge when it come to low output moving coil cartridges.

The loading is killing a high frequency resonance that is ultra-sonic or ever Radio Frequency (RF) in nature. If your preamp does not care about that energy being injected into its input, the loading will have no effect. If you preamp doesn't like that energy, you will hear the effects of the loading right away.

I like 100 ohm on my Helikon SL.

I like 100 Ohms with all moving coils in general and that's what most phonostages do as default.

1000 ohms really opens it up...wider sound stage, greater 3D effect (Etna)