Functions that must be handled by the older fwm daemon on a SMS/MDS generally cannot be automated through the API as fwm is not API-aware. Any management function being handled by the newer cpm daemon can potentially be accessed through the API. So as far as I know the inability to perform an Install Database via the API is more of a technical limitation of fwm than anything else.
A common question I get in the CCAS class is what management functions cannot be handled through the API, and must be performed in the SmartConsole GUI:
https://community.checkpoint.com/t5/API-CLI-Discussion-and-Samples/Functionality-API-vs-SmartConsole...
Pretty much all the functions listed are handled by fwm (hence the need to use the old SmartDashboard GUI to work with many of these functions), looks like performing an Install Database operation needs to be added to the list.
Attend my online "Be your Own TAC: Part Deux" CheckMates event
March 27th with sessions for both the EMEA and Americas time zones