I'm not sure what's your problem.
Units_stats_land_tables
Code:
euro_line_infantry_sweden 160 0 0 euro_officer2 euro_drummer1 euro_standard_bearer euroline infantry_euro_medium man_musket x_euro_musket 3 leather 1 0 0 False musket 40 25 0 flintlock musket_flintlock 20 foot_musket plug_bayonet 6 9 12 0 foot_bayonet 0 drill_set_infantry_line trained 7 3 0,85 1,3 2,2 4 0 0 20 0 False False True False False False False True False False False False False False 200 300 400 False False True False False False False False True False False True False False False
Model name: euroline
unit_tables
Code:
euro_line_infantry_sweden Line Infantry infantry infantry_skirmishers 780 740 1 920 230 12 True infantry_musketmen euro_line_infantry euro_line_infantry euro_line_infantry europe 0 mp_infantry True True True 0 False 0
To change the type of unit, icon, info image, ....
Copy the two lines (clone) and make your changes. Obviously you can not modify vanilla units without cloning them (but you can maintain the name for not having 2 units).