I think your suggestion for a last edited date in the rules is a good one.
However, the part you're quoting there was specifically noted in the US English "Welcome to Season 10!" post:
As announced previously, teams with great players will sell more merchandise. More fans want to wear the jerseys of players who are amongst their league, division, country, or even world leaders. Further, fans prefer wearing the jerseys of players who grew up close to home; domestic players sell more merchandise than foreign players, and fans get particularly excited if they can watch one of your own draft picks lead your team to prominence. On the other hand, fans have seen too many high-priced players who can't deliver when it matters. It's performance that matters, not salary.
Maybe it got lost in the Czech translation, I don't know.