How do you balance the need for immediate feedback through leading indicators with the longer-term tracking of lagging indicators to measure the success of a GTM strategy, and how do you ensure that attribution across cross-functional teams remains clear and actionable?

Based on the language you used in your question, I think you already know the answer!  Balance is the right word because the leading and lagging indicators measure very different dynamics.

The leading indicators - I think about engagement, clicks through rates, paid ad conversion and sales pipeline - are all measuring top and mid funnel dynamics.  Those are a really good reflection of the success of your launch messaging and your ability to gain eyeballs and attention and can give you an early indication that you are on the right (or wrong) track. But you really need the down funnel metrics  -  revenue, churn, NPS, CSAT - to know if you’ve got a truly viable product in the market. 

To the point I made about very different dynamics, having great looking leading indicators doesn’t mean customers will convert or pay what you want.  And having weak leading indicators also doesn’t mean that the customers that are in your funnel won’t convert and won’t pay.  So you really need the two together to complete the full picture.

I'm not sure I'm tracking the second part of your question about attribution. Is it attribution you're worried about, as in making sure that the results are trackable down to a person? Or maybe it's about accountability? Not sure but feel free to DM me on LinkedIn for more clarity.