It's the skip rate...
By skipping the FG, you don't increase the TTW and you only lose the electrum.
In general the formula sheet, it's one of the inherent problems with the original FGei and carries over with this one.
The idea that you should skip certain FGs to increase the electrum rate is valid, but is to be applied after the data is gathered, instead it's gathered as part of the data.
So if one tester enters skips and another tester does not you get a totally different FGei score.
It's one of three problems with these tests
1.) Testing error (Including Skips)
2.) Different FGs have different card giving abilities, instead they went with the average, which is significantly wrong.
3.) The tests are done on random, so unless the tests were done in an even 10 games per FG, you will have error for a long time, normalization will even it out but it requires meeting that minimum before the numbers stabilize.
The thing is FGei still is good enough to give you a feel for where a deck stands so people still go with it.