Thank yoy for your interest and answers.
Platonides:
So you shouldn't have tried to convert the
content, that would have
broken it.
Very likely this is what they did.
Without knowing the exact way your db is broken,
it'd be hard to fix it.
What search are you using? The internal one? Maybe you can share a
one-revision sql dump?
And your crystall ball? ;-) Well, as to the problem with the search I've
discovered the key for the searchindex table is generated with U8<hex>
while the table has u8<hex>. So, if I replace in SeachMySQL.php
$searchon = $this->db->strencode( $searchon );
by
$searchon = $this->db->strencode( $wgContLang->lc ($searchon) );
words are found. I'm using this as a workaround, but I'm investigating
the origin of the problem (any hints?).
PS: Update to 1.15.2, you are vulnerable to CSS image
inclusion.
Thank you. Please, could you give a pointer explaining it?
Cheers
Javier