The OCONV conversion seems to be applied only to the suggested words, not to the root word or to the morphological analysis.
For example,
$ cat oconv-root.aff
ICONV 1
ICONV a ei
OCONV 1
OCONV ei a
SFX A Y 1
SFX A 0 s .
$ cat oconv-root.dic
1
eiei/A
$ hunspell -d oconv-root
Hunspell 1.2.8
aa
*
aab
& aab 1 0: aa
aas
+ eiei
$ hunspell -m -d oconv-root
aa
aa st:eiei
$
Also XML API of Hunspell (it will be used by OpenOffice.org thesaurus) lacks of OCONV conversion.
I will start looking into the first reported issue, but please log a different bug report for the XML issue.