There is no "right" loading for Koetsu. It totally depends on the phono stage you’re using, and your preferences. Since you’re using the same phono with 2 Koetsus, the difference there can be attributed to voicing differences across models.
I used to think Koetsus should always be loaded 100 ohms or less - but then on an ARC Ref 3SE, my favorite load for Blue Lace ended up being 200 ohms. On others I’ve liked 50 ohms. Proponents of the Herron (and others) will say "infinite" load (much higher than 100K) is best, but I certainly liked it better with more "typical" loading.
Anyways, I’m more likely to use Koetsu with a SUT. There, you should pick a ratio 15x - 30x (depending on model) and just use a 47K ohm MM input. Whatever the actual loading works out to from that - is easy to calculate (50 - 200 ohms), but doesn’t matter nearly as much as picking the right ratio in a good sounding SUT.
Final note - Koetsu are 5 ohm coils, so you will run into significant signal losses below (say) 30 ohms. Don't go below that.