Thanks Jan for the additional information. I've seen similar partial spoilers extensions on bumpy landings in real world videos. But I was not sure about the logic involved on it. Now with your explanation about wheel spin and gear strut full compression, makes total sense.
This makes me amaze even more about the level of detail involved in the IXEG 737. As it reproduce all this logic perfectly (except sometimes on replays).
Yesterday I did further testing, and the spoilers animation was perfect during replay mode on XP11.10. I've still not found any explanation why sometimes work, sometimes don't.