Hardhat generates the source name in the format as a relative path to the file containing the source while this plugin adds the name of the source file with the name of the contract appended.

This plugin:

"sourceName": "L1CrossDomainMessenger.sol:L1CrossDomainMessenger"

Hardhat:

"sourceName": "contracts/L1/messaging/L1CrossDomainMessenger.sol"

The offending line is here: