Excellent ideea about asking for community suggestions on new units.
I would have some suggestions for the late campaign (1816 - 1825) in the Balkan area which is usually an area always lacking. Depending on how you have your emergents planned in the Balkans I would suggest having a look at the
National Revolutions mod. Sotericus has used historical information from military atlases to create the Wallachian and Moldavian units (or in your case for Romania should you not want to have the two historical emergents, even though Romania was united in 1853, while the two principalities existed as autonomous entities within the ottoman empire since the 16th century and had various levels of de facto independence from 1821).
While the professional armies of the principalities were not insituted until 1830 there are plenty of militia units to be created.
For example
Dorobanti de plasa
Slujitori
Im sure Sotericus would be more than happy to share his units so that you do not have to double up on any work. He also has worked on the Greek and Serbian units for the 1821 period.