FOP can't handle mixed-case words (for example German nouns) as hyphenation exceptions, for example "Dateiname" (file name) which is hyphenated as "Datein-ame" ("Datei-name" would be correct). The words in the stoplist are mixed-case. However, when FOP checks if there's an hyphenation exception for a certain word (that is, it is in the stop list), all the characters of the word have already been converted to lowercase. Therefore mixed-case words in the stoplist cannot be found. With the attached patch applied, FOP enters the exception words in lowercase into the stop list.
Created attachment 19443 [details] Patch to convert exceptions to lower-case
A better solution is to normalize the word using the character classes defined in the hyphenation file, rather then doing a plain toLower.
resetting P2 open bugs to P3 pending further review
increase priority for bugs with a patch