As an FYI for others - I am in Cathay’s lounge right now. Transfer easy, just takes ~25min from T1.
No trouble with boarding passes, not asked for during transfer.
At arrival in T4 is security screening (own queue for the bus, no one there). Afterwards a guy checking boarding passes and he made a note in a log for travelers of other terminals.
That’s all.
Cathay’s lounge definitely is better than the Sats.