So either there are some other regulations about replacement of injured players or FIPAV indeed got a special treatment as a host. Although I don't know if this is any valid in reality considering it says that 'it is limited to a maximum of 24 players, out of which 14 players will eventually participate in a match', considering that on CEV website Italy or Poland have +30 names submitted.
On the old CEV site there are 24 names squads. On this print it says that there is a possibility to change injured player but only by someone from long list. The replacement should be someone included before. Antropova couldn't be because she was not Italian.