It's magic!
yarn test
The Kashi code is licensed from BoringCrypto and is licensed only to Abracadabra.
Deploying contracts\CauldronV2MultiChain.sol seems to cause problem once it's time to verify the source code on etherscan-alike with solc-input. Sending solc-input has the advantage of not requiring sending the whole source code for verification.
But it fails at the verification process, etherscan-verify mention older solidity version might cause the issue: ethereum/solidity#9573
At this stage, etherscan-verify then tries to submit the whole source but also fails as the source code is too large to be sent for verification.
A workaround is to use the CauldronV2Multichain version in contracts-flat folder and use the following solc parameter when compiling:
"contracts/CauldronV2Multichain.sol": {
version: "0.6.12",
settings: {
optimizer: {
enabled: true,
runs: 999999,
},
},
},
This might also be caused by pragma experimental ABIEncoderV2; which is present in unflatten CauldronV2MultiChain but not in the flatten version, but further experimentation would be require to confirm it.