Some calendar fields might have ambiguous values depending on the language:
One example is the japanese calendar. The emperor Shōwa exists 3 times. When parsing a date string, the first emperor is used. Most probably the last one is correct.
The following source shows the example:
This could be resolved by changing the method matchString. Changing
"if (length > bestMatchLength ..."
"if (length >= bestMatchLength ..."
would have the result, that always the last matching is used.
Of could finding new unique emperor names would be the best solution.