I am using a custom .bst file and title "t" change.case$ does not seem to work. It changes the cast to lower or upper when used with parameters "u" or "l".
My format.title function:
FUNCTION {format.title}
{ "title" bibinfo.check
title "t" change.case$
duplicate$ empty$ 'skip$
{
"\enquote{" swap$ *
"}, " *
}
if$
}
Another example:
In .bib file the title is
title = {Grandmaster level in StarCraft II using multi-agent reinforcement learning}
and the output produced:
It looks like it is changing it to a sentence case and not title case.
Another example
title = {the title of the work}
and the output is:

But when I change a line in format.title to title "u" change.case$ I get:

This is very strange behaviour. Do you know how to fix it?
EDIT: The expected output is "The Title of the Work" (see). I want to achieve the title case.

"t" change.case$does “title casing”: all letters are made lower-case, except for the first one. The output seems correct. – Phelype Oleinik Jul 05 '20 at 15:27"t" change.case$does what I would call 'sentence case'. It transforms everything but the first letter (and the first letter after a colon plus a space) to lowercase. The standard solution is to input the fields in Title Case in the.bibfile and let BibTeX convert it to sentence case if required. (cf. https://tex.stackexchange.com/q/166616/35864, https://tex.stackexchange.com/q/439440/35864) – moewe Jul 05 '20 at 16:10