Hello Detlef,
That looks like a Maguindanao blade, indeed. Please post dimensions!
Possibly upper Cota Bato region and maybe after 1910? (The engraving looks a bit crude, too.) Does look like this kris had seen serious action and wear though...
IMHO it should be possible to nicely reglue the repaired crest - no need for grinding, just carefully remove the old glue (some water (damp towel) may help to get it loose), dry carefully and glue again. The break should be almost invisible except for the minute chipping (which could be filled). The wooden pins (bamboo?) will do fine - apparently the glue failed.
Wetting the rattan will allow to get it off without breaking anything. I can't guarantee that the dried rattan will hold the pommel tight again but at least in theory it should...
Regards,
Kai