Using the 'setblock' action in combination with the 'breakevent' results in the 'breakevent' passing but the 'setblock' portion not occurring.

This is the example I used to test that the message did pass through but the block was never replaced to the new block type.

{
"block": "minecraft:log",
"message": "Log detected!",
"setblock": {"block": "minecraft:wool"}
}

However using the same example works in combination with the 'rightclick' event instead.

The problem is that you need to add "result": "deny". Because you let the break go through which means Minecraft itself will replace the block with air AFTER the wool has been put there