Your right I did forget the multiweapon penalties. How about I add this:
Feat: In combination with its natural abilities, a statue of Kali's Multiweapon Fighting feat allows it to attack with all its arms at no penalty.
That wording comes from the marilith demon.
That fixes the issue without increasing its strength. Yeah, it's a tad weak but I think I like it that way. It's hollow, which should be reflected in its stats.