My programming/modding skills do not exist, but I can at least edit the existing Units.csv file and share it, hoping that I did not mess up things in the process.
For now I've only edited Polish equipment and related as it's close to home, but if this works, I might sometimes add more of such changes here and there. Possibly this will be inspiring and fun to use. My initial try included changing some stats plus adding a few units that are variants utilizing the same models (since I have no way to add new textures/models/meshes). I am not sure if for these new models I did not mess up cross-file references, but it seems that the only thing I should not touch is column AD (model) to keep the intended model being used, but I'm not sure about the A, B and C columns and if editing things in names can break any references. Tips about this are greatly appreciated - worst case scenario I'll refrain from adding anything new and just edit existing units.
EDIT - apparently messing with unit names crashes the game upon loading missions where they exist (probably due to "name" in column A). Adjusted.
Still no idea how to properly encode Polish characters in the csv, but that's a minor thing.

Changelog:
0.1
GLOBAL
Horse Transport
Service changed to 01.05.1919 - 01.01.1946
POLAND
FT-17
Service changed to 01.05.1919 - 01.01.1940
7TPjw
Service changed to 01.01.1936 - 01.01.1940
7TPdw
Service changed to 01.01.1936 - 01.01.1940
TKS
LowProfile trait added - part of global tweak planned to use LowProfile for tankettes and certain other vehicles like the Hetzer
Service changed to 01.01.1934 - 01.01.1940
TK-3
NEW UNIT - earlier TKS variant (same model used)
Ground Defense down to 8
LowProfile trait added
Prestige cost down to 100
Service 01.01.1931 - 01.01.1940
TKS nkm
NEW UNIT - TKS variant with a 20mm auto-cannon (same model used)
Hard Attack up to 10
Initiative up to 5
LowProfile trait added
Prestige cost up to 120
Service 01.01.1939 - 01.01.1940
Renault R35 - same as French variant, different service
Service 01.07.1939 - 01.01.1940
SP wz. 29
Soft Attack down to 11
Ground Defense down to 9
Air Defense down to 5
Speed down to 50
Prestige cost down to 110
SP wz. 34
Ground Defense down to 9
Air Defense down to 5
Speed down to 60
Prestige cost down to 130
Truck
NEW UNIT - FR truck clone (should be Italian due to Fiat licensing in pre-war Poland, but the models do not match too well)
37mm wz. 36
Service changed to 01.01.1936 - 01.01.1940
75mm wz. 1897
Renamed to 75mm wz. 1897 from 75mm wz. 97
Speed up to 20 - part of global tweak planned to change all 75mm field cannon speed to 20 to give a better reason to use these
Service changed to 01.01.1919 - 01.01.1940
105mm wz. 29
Service changed to 01.01.1930 - 01.01.1940
155mm wz. 1917
Renamed to 155mm wz. 1917 from 155mm wz. 17
Service changed to 01.01.1919 - 01.01.1940
PZL P.7a
NEW UNIT - PZL P.11c variant (same model used)
Air Attack down to 4
Ground Defense up to 4
Air Defense up to 5
Initiative up to 3
Prestige cost down to 40
Service changed to 01.06.1932 - 01.01.1940
PZL P.11c
Ground Defense up to 4
Air Defense up to 5
Initiative up to 3
Prestige cost up to 60
Service changed to 01.01.1936 - 01.01.1940
PZL.23B Karaś
Renamed to PZL.23B Karas from PZL P.23B Karas (P was reserved for fighters by Puławski's design)
Air Defense up to 3
Speed up to 160
Prestige cost up to 90
Service changed to 01.01.1937 - 01.01.1940
PZL.37B Łoś
Renamed to PZL.37B Los from PZL P.37B Los (P was reserved for fighters by Puławski's design)
Soft Attack up to 10
Air Defense up to 9
Speed up to 170
Prestige cost up to 240
ROMANIA
PZL P.11f
Ground Defense up to 4
Air Defense up to 5
Initiative up to 3
Prestige cost up to 60
Service changed to 01.01.1936 - 16.10.1941
PZL.37B Los
NEW UNIT - PZL.37B Los (same model used, same stats)
Service changed to 01.10.1940 - 01.01.1945
BULGARIA
Renamed to PZL.43 from PZL P.23B Karas (export variant name)
Service changed to 01.04.1937 - 01.01.1946
ROMANIA, BULGARIA, GREECE, TURKEY
PZL P.24
NEW UNIT - PZL P.11c variant (same model used) - I did not divide into individual variants as it would be overkill
Air Attack up to 8
Ground Defense up to 5
Air Defense up to 6
Initiative up to 4
Prestige cost up to 80
Service changed to 01.01.1938 - 01.01.1942



