G'day,
while i can´t comment on the PP-specifics, i´m almost sure the brand offered full-fire enamel dials as replacements for the 2526 very recently. Did they stop this service?
Here´s one, same source as other enamel dials by PP for the current portfolio:
This one is a sample from production and not very old; it´s broken during the firing process, hence no use for service needs.
I´d guess applying RG or YG index markers should be a minor task, as long as either is available or the brand wishes to have them re-produced.
Short sense of long story; if there´s no chance of getting a genuine enamel replacement enamel dial, i´d keep the original one.
Cheers,
Peter