Generating a conductor's lead sheet for a big band chart?

The definition of "conductor's lead sheet" seems a bit self-contradictory to me.
Maybe a "condensed" score was meant?
This is a manual operation. // And it takes more work.

Condensed scores are of two types: old-style and new-type:

Old (fully condensed): usually consists of three lines. If I simply exemplify: The melody is at the top, the chord accompaniment and counter melodies are in the middle, and the basses and bass accompaniments are at the bottom.
The instrument changes and are indicated in text. eg: "Fl, Clar. and Trbn.", "Tprts & Alto".
Preparing it's a bit more laborious, requires attention and habit.
(After rehearsing with the full score, it may be easier to conduct with it since the conductor memorizes the arrangement) .

New (moderately condensed): instruments are divided into several groups. woodwinds on the top line, trumpets on the next line, horns and saxes on the next line, and trombones and bass on the bottom. (It can reach up to five or six lines)

In the full score, did you have 'Hide empty staves within systems checked in Format > Style > Score? Doing so will reduce the full score somewhat.

I assume you're talking about something like this:

https://s3.amazonaws.com/halleonard-pagepreviews/HL_DDS_1045429dXxbIfn6…

Basically, a lead sheet that's been marked up with indications as to who is playing what. There is no AI that could produce something like that automatically, but it would be a simple enough matter to add a new staff and copy relevant info to it from the existing staves, add markings as staff text, etc.