[booleanbetrayal]

Assuming sourcemap pipelines work, open your browser and put debuggers on anything you don't understand tracing requests / invocations. Start with something conceptual like a particular page / component and work your way out beginning at the request entrypoint. Along the way you will likely figure out things like authentication management, routing, view hierarchy and design patterns leveraged, etc. Allow a particular issue you need to resolve guide you if needed, but don't sweat the learning curve, as it is required and should be expected.