In the excel files, there's a method called GetRicRules, which converts a RIC to a target depending on the parameter.
GetRicRules function is implemented in the COM library XMALib.dll installed with Eikon. XMALib.dll does not provide a public API and was never documented for external use. As @chavalit.jintamalit said there's no equivalent to GetRicRules function in public Eikon APIs. You may be able to use XMALib.dll in Python with win32com.client module of pywin32 package. I haven't tried it myself, but apriori I don't see why this wouldn't work. However since XMALib.dll is a 32-bit library, it cannot be used in 64-bit Python. Since XMALib.dll does not provide a public API, there's no external facing documentation for it and Refinitiv assumes no responsibility for service continuation if you use it. In other words you can use it at your own risk. It's very likely that this library will not be included in the next generation of Refinitiv end user terminal known as Refinitiv Workspace.
I could not make the formula you provided in your question work on Eikon Excel.
I also cannot find any reference in the helps.
Anyway, if it is build-in function in Eikon Excel, it is not available on Eikon Data API(Python).
For available function on Eikon Data API, please refer to this API reference.
I am trying to get daily close price data using RIC list and the eikon get_data api is only able to return result for 2000 odd rics and throws Backend error 400 Bad Request for remaining.Is there a way to get close price data for some 6000 rics?