In order to find and correct Legacy Lava, do the following:
Set Lava Support Level to 'LegacyWithWarning'. This is found in Admin Tools>General Settings>Global Attributes>Lava Support Level.
Legacy Lava Errors will show up in the Exceptions List. Look specifically for Legacy lava.
View details from the document icon on the right of the error. The warning will tell you where and the incorrect syntax might look like this: Warning: Legacy Lava Syntax Detected: Workflow.WhatisBroken
Find the error. In this example I found the Legacy lava in the linked workflow. It looked like this: <p>What is the Maintenance Request? {{ Workflow.WhatisBroken }}</p> I updated it to this: <p>What is the Maintenance Request? {{ Workflow | Attribute: 'WhatisBroken' }}</p>
Check the exceptions list the next day to see if there are any other errors.
*Knowledge gained through time spent with Mason Kinyon.