After Hana didn’t reveal her own name and they insisted on knowing it, Hana turns it around and says that Syaoran’s name isn’t his true name either. Syaoran and the rest realize she must have gotten this knowledge from somewhere, perhaps even have checked up on them before.
As I skimmed the raws earlier, I saw Sakura and Hana together, so I can only assume that is how she knows this information.
Which if Sakura was willing to reveal what his name was or at least that Syaoran had another name, the situation for everyone is going to get a lot worse because that implies Sakura knows something that is going to happen and is trying to do what she can for them.
As we know peoples name are very important and by keeping ones name a secret it is usually in protection of someone (Which must be why Tachibana and G7!Sakura are keeping Hana’s name a secret). So if Sakura gave Hana this information it means that she trusted her enough that she would help them, or perhaps have Syaoran and the others help Hana.