I am working with cleaning up a lot of legacy things in an org I recently came into.  In one case, there is a process that I think will work just as well, if not better, as a regular formula field.  However, copying over the formula in it, I am getting a Syntax error. Missing '='

Here is the formula:

IF(
    OR(
        ISPICKVAL([Account].CS_Relationship_Health_Score__c, "Red"),
        ISPICKVAL([Account].CS_Adoption_Health_Score__c , "Red"),
        ISPICKVAL([Account].CS_Product_Health_Score__c , "Red"),
        ISPICKVAL([Account].CS_Services_Health_Score__c , "Red"),
        ISPICKVAL([Account].CS_Support_Health_Score__c , "Red") 
    ) ,
"Red",
    IF(
        OR(
            ISPICKVAL([Account].CS_Relationship_Health_Score__c, "Yellow"),
            ISPICKVAL([Account].CS_Adoption_Health_Score__c , "Yellow"),
            ISPICKVAL([Account].CS_Product_Health_Score__c , "Yellow"),
            ISPICKVAL([Account].CS_Services_Health_Score__c , "Yellow"),
            ISPICKVAL([Account].CS_Support_Health_Score__c , "Yellow") 
            ) ,
    "Yellow",
    "Green"
    )
)

Facing issue while merging accounts in salesforce with apex 

Error : Invalid field IsPartner for merge