According to some sources, it looks like it was something called a "replay attack".
Not necessarily. It could be someone consolidating coins in their own wallet for a second time. A "replay attack" would carry some serious speculation, including that the recipient of the funds would have kept their wallet and private key for 10 years.
Any transactions on these old wallets that occurred later after that block can be replicated on the new chain.
As long as certain conditions are met, like balances and destination addresses.
The entire integrity of this "revival" Luckycoin is now compromised.
What a mess.
Seems like a standard hazard in such an undertaking. You're assuming that the "attacker" would somehow have access to recipient addresses, because they of course can't be recreated. BTW you missed my last question:
If anyone can do it, why didn't the "revival" do the same thing I did and decide to prune the block data to start at 81k instead?
How do you know they pruned the block data?