For S/4 HANA OnPremise, we have the following FAQs:
2578294 - FAQ - Employee to Business Partner synchronization in S/4HANA OnPremise
2409229 - Employee Synchronization Report: FAQ
and for S/4 HANA CLOUD:
2555311 - FAQ - Import Employees app
and for SF integrated with S/4 HANA CLOUD:
2882329 - Common issues during the SF -> S/4HC replication
and for the usage of the API Replicate Basic Master Data for Workforce from External HR Systems
2905918 - FAQ: Replicate Basic Master Data for Workforce from External HR Systems
