The comp plan is the same for all. The percentage and weight is different. Cross sell gets a regional target and is shared.
Fair would be the right balance of comp. Again if one CSM has 5 3 year deal and only 1 one year deal, they will have to wait for 3 years to get comped on most of their renewals.
What would "fair" look like in your situation? Would that mean each CSM has the same number of renewals to handle in a given year?
Are upsells a potential source of revenue for your CSMs as well?
My company's CSMs handle both upsells and renewals. Some CSMs have portfolios with greater or less revenue potential than others, so we adjust their comp plans accordingly. Some CSMs have comp plans more heavily based on revenue potential and some have plans based almost exclusively on client retention rather than revenue.
Do all of your CSMs need to have the same comp plan structure?