I'm finding on arbitrating the USHMM Czech Republic Selected Jewish Holocaust Records that quite often both keyers have apparently keyed the month name as brezen instead of březen or zárí instead of září. I think I've seen the same problem with říjen too. And the same with the c with caron in červen and červenec.
(The keying tool takes me to that field telling me to arbitrate it although the two keyers' values match. This is just as well since it needs correcting.)
Is it possible that the month names were keyed correctly / selected from the dictionary, but lost the caron on the way to arbitration, or is it another Mac keying tool thing? It seems unlikely that a keyer would key the vowels with diacritics but not the c and r? It's going to downgrade their accuracy stats, unfortunately.