Please note that we've updated the Mount & Blade II: Bannerlord save file system which requires you to take certain steps in order for your save files to be compatible with e1.7.1 and any later updates. You can find the instructions here.
Nerfing speed of Skirmishers renders them useless. Are you really going to choose a class that takes a massive hit to armour, receives an insignificant amount of movement speed and only gains like 1-3 javs for an extra +20 gold cost. They need to buff the speed or make Skirmishers cheaper than light inf/warriors/peasant class.