I'm surmising a tacit agreement has been reached to compensate...

I'm surmising a tacit agreement has been reached to compensate KCN for Chatree reopening costs and probably including cost of celebratory events and bonuses.
Governments demand to see actual invoices and will not entertain ambit claims as they are answerable to taxpayers.
Hence the delay in settlement until Plant #1 is fully commissioned and the final bills received.

AFL finals, Melbourne Cup day, Australia day are being celebrated to highlight the Australian nature of the operation and to focus the Thai govt on the TAFTA free trade agreement, with the Australian ambassador's attendance meant to highlight the point.
None of other cases eg Walter Bau, Hopewell benefited from the backing of a bilateral trade treaty.
Thailand FDI is declining relative to Indonesia & Malaysia and a brazen breach of a bilateral trade treaty will be the final nail in the coffin.
KCN Management has a reputation for being hard nosed negotiators with a proclivity for excessive secrecy.
The CEO of RIO in Chile has attested to this.
Patience and faith in management is the name of the game.