It should work. For example if you want a Ki Bekko koi: name the name tag "ki bekko" or "koi 10" or simply "11" and than use it on a salmon! If you include the "|" symbol it will not work, it is only a separation marker!

Regarding the numbers, the "skins.x=a b c" line calls for which skins the later property will apply like "weights.x=a b c". So "a b c" in use "1 2 3" will call for the "salmon1 salmon2 salmon3" skins.
The "x" is a counter to differentiate between skins and their properties.
In the property lines like "weights.x=" the numbers are the values of the property and will apply changes to the skins in the same position as them in the row of numbers.

So it should look like this if I want "salmon1 salmon2" to have a weight ratio of 10:1 but I want "salmon3" to spawn only in swamps.

skins.1=1 2
weights.1=10 1

skins.2=3
biomes.2=swamp

I hope this helps and enable random textures in optifine!