luatex-cache

[Bob Tennent]

 >|When and how does this get refreshed "automatically"?
 >|And if it isn't, what is the "official" way of doing
 >|it, for both ~/.texlive2019/texmf-var/luatex-cache and
 >|$TEXMFSYSVAR/luatex-cache.

I'm not getting any answers so let me explain why I'm
asking. On one system a simple file that uses libertine.sty
compiles using xelatex and lualatex with no fontspec
warnings. On other systems, lualatex generates warnings as
follows:

Package fontspec Warning: OpenType feature 'Numbers=Uppercase' (lnum) not
(fontspec)                available for font 'LinBiolinum_RB' with script
(fontspec)                'CustomDefault' and language 'Default'.

Package fontspec Warning: OpenType feature 'Numbers=Monospaced,Lining' (tnum)
(fontspec)                not available for font 'LinLibertine_RZI' with
(fontspec)                script 'CustomDefault' and language 'Default'.

etc.

Yet xelatex does *not* generate warnings. So I'm
conjecturing the luatex-cache needs to be refreshed but
nothing I do manages to avoid the warnings on the relevant
system.

AFAIK, there should not be any warnings.

  % otfinfo -f  LinBiolinum_RB.otf | grep lnum 

generates 

lnum    Lining Figures

and

  % otfinfo -f LinLibertine_RZI.otf | grep tnum

generates

tnum    Tabular Figures

What is going on?

Bob T.