There is no Guide or DOC thats spells this out for you, lineage guide wont help you. My recommendations are as following:
1. Try to understand the general logic of all OBIA facts...there is a SDE extract, SIL, and PLP process. This applies to all areas, not just HR
2. Understand the grain of the FACT table in question. For instance, for HR, there is a MONTHLY (W_WRKFC_EVT_MONTH_F) fact table that aggregates yoour headcounts, HR events, at the MONTHLY level. Also, there are various types of transactions in this table incluing EVENTS, JOBs, etc. This is fed from a more granular fact such as W_WRKFC_EVT_F table. Its possible these are using CSV file lookups, etc that you configure.
3. Once you understand the target Facts, you can then go to the other SDE mappings to understand how they go from Sourse-> staging. For example, you will see the SQL calculating the baseline logic.
The docs can help give a general idea but you have to do this type of analysis to really understand the logic.
if helpful, mark correct