Germany OTL had 99 capital ships available for Jutland, more under construction.
Japan OTL had 15 capital ships including captures from the Russo-Japanese War, minus whatever Japan lost fighting the US.
Reaper, I think you are mixing up overall ship numbers at Jutland with capital ship numbers.
I don't have the figures for pre-dreadnoughts to hand, so this is from memory. IIRC, assuming no losses from the war, the Germans would have had in 1917 -
24 pre-dreadnoughts
19 dreadnoughts (+2 if no wartime construction delayed)
7 battlecruisers
Judging from the Naval Laws, Germany's absolute peak capital ship strength OTL would have been approximately 50 ships (4 dreadnought battlesquadrons, 3 reserve/flagships and an indeterminate number of battlecruisers.)
Absolutely overwhelming against Japan OTL I agree; and although not directly comparable to TL-191 considering the date of the POD, relative Industrial strengths suggest that this would still be true in TL-191.
The only argument I can see in support of Turtledove is "where are all these ships going to coal?". Britain seems to have come out of WWI intact enough not to have to give up basing rights, the Netherlands is neutral, Japan owns the Phillipines so the position of the US is moot, Vladivostok, while a possibility given the defeat of Russis, is too exposed and Indochina's coastal regions would be the first target of the Japanese once France collapsed. Fighting Japan while basing coal powered ships out of East Africa strikes me as a dubious proposition.