I can't speak to the missing formations as I tend to cross attach sub-units to taste rather than buy pre-built company formations. The Japanese OOB is more obfuscated than most anyway.
As for the mortars, once again the designers have accommodated two opposing camps rather nicely. There was a long and acrimonious discussion on the yahoo lists on the matter. The basic split was between grenade chuckers such as the 2" and type 89's with limited sighting and the more advanced German 50 mm with proper sights etc. Lip service was given to the similarly equipped US 60 mm.
The up shot as I recall was the splitting of the mortars into organic direct fire support versions that use Z key fire to hit dead ground and mortars proper in independent teams that could be bought if players wished to use the indirect versions.
So if you want indirect Type 89's, don't buy them as part of a company, buy them separately and cross attach.
Oh and good luck with the masses of 1 pt Chinese armour.
