This is a hugely incomplete list. As I've already said, many mods' units will be supported with no further work needed. This is only a list of units that I've specifically looked into.

Partial Support: Units that are partially supported will pass on base stat differences, but their abilities aren't inherited. For most of these, I've already looked at adding support and ruled it either unfeasible or not worth the squeeze.

Partial Support:

• Mongolian Hui Hui Pao
  
• Norwegian Ulfhednar
  
• Khmer War Canoe
  
• Mali Sofa
  
• Persian Warship
  
• Chinese Shigong
  
• Kongo Medicine Man
  
• Aztec Warrior Priest

Full Support: Everything else.

Partial Support:

• Akkadian Nas Qasti
  
• Armenian Ayrudzi
  
• Norman Familia Regis
  
• Seleucid Argyraspides

Full Support:

• Berber Arer Warrior
  
• Filipino Katipunero
  
• Indonesian Cetbang
  
• Malaysian Lancaran
  
• Malaysian Pesilat
  
• Norman Man-At-Arms
  
• Romanian Calarasi
  
• Romanian Vanatori
  
• Sassanid Aswar
  
• Seleucid Elephantarchia
  
• Seljuq Sarbaz
  
• Songhai Bari Koy
  
• Swiss Reislaufer
  
• Taino Macana

This list is far from complete.
Partial Support:

• Tongva Ti'aat
  
• Witcher Domrey

Full Support:

• Atelier Linca
  
• Atelier Puni
  
• Bilqis Qayl
  
• Brazilian Pracinha
  
• Burmese Myinsi
  
• Ethiopian Shotelai
  
• Gaul Oathsworn
  
• Hawaiian Kaimiloa
  
• Hawaiian Koa
  
• Hittite Ansukurra
  
• Hyperdimension Neptunia: Planeptune Civilization units
  
• Jerusalem Crusader
  
• Mexican Chinaco
  
• Russian Skeleton (Valkrana)
  
• Siamese Chang Suek
  
• Soviet Pekhota
  
• Soviet T-34
  
• Tibetan Rta Pa
  
• Witcher Units (Except Domrey)