You can run Info-validate only on a single Info file that has a
tag table. The command will not work on the indirect subfiles that
are generated when a master file is split. If you have a large file
(longer than 70,000 bytes or so), you need to run the
texinfo-format-buffer or makeinfo-buffer command in such
a way that it does not create indirect subfiles. You will also need
to create a tag table for the Info file. After you have done this,
you can run Info-validate and look for badly referenced
nodes.
The first step is to create an unsplit Info file. To prevent
texinfo-format-buffer from splitting a Texinfo file into
smaller Info files, give a prefix to the M-x
texinfo-format-buffer command:
C-u M-x texinfo-format-buffer
or else
C-u C-c C-e C-b
When you do this, Texinfo will not split the file and will not create a tag table for it.