IFS spreadsheet function lacks help (ad of current master towards 6.4). Introduced in tdf#97831 for 5.2 [1]. [1] https://wiki.documentfoundation.org/ReleaseNotes/5.2#New_spreadsheet_functions
Patch already done https://gerrit.libreoffice.org/plugins/gitiles/help/+/7b20c74a33942157b02b99353aa98e45f7c0a111%5E%21/ The help page is here https://help.libreoffice.org/6.4/en-US/text/scalc/01/func_ifs.html?DbPAR=CALC#bm_id901556242230198