Getting started in Excel Labs Custom Modules (missing "publish" step)

First-time poster — please be gentle!

Context

• Excel for Mac
• I have a large library of LAMBDA formulas and wanted to manage them using Excel Labs
• In particular, I wanted to organise formulas into custom Modules

Issue

How to actually activate functions defined in custom Modules in Excel Labs

I recently discovered Excel Labs and was very excited to use it to manage and structure a large library of LAMBDA formulas.

My goal was straightforward: create custom Modules to organise formulas by purpose, and then use those formulas in the workbook.

However, it took several hours of experimentation and debugging — even to get a trivial example like:

ABC() = 12

to work when defined in a custom Module.

The missing piece (which Copilot, Google searches, and the README all missed) is this:

Functions defined in custom Excel Labs Modules are inert until the module is imported into the special Workbook module.

Until that import step occurs, functions in custom Modules:

• do not appear in Excel Labs → Names
• do not appear in Formulas → Name Manager
• are not callable from the grid

According to Copilot this behaviour is not currently documented, and the UI strongly suggests that custom Modules are “active” by default — which they are not.

Working workflow (for others who hit the same issue)

This is the workflow that finally made things work for me (possibly sub‑optimal, but reliable):

1. Create and maintain functions in custom modules (e.g. Transformations)
2. Explicitly import the required functions into the Workbook module, e.g.:

TransformAtoB = Transformations.TransformAtoB

Workbook module now publishes to:

• • Excel Labs → Names
  • Formulas → Name Manager

This makes conceptual sense — maintain a large structured library of formulas (or import libraries from GitHub), only activate the formulas required by a particular workbook.

But without documentation, it’s very easy to assume custom Modules are active by default.

Why I’m posting this

When I finally asked Copilot “Why didn’t you say this up front?”, the answer was essentially:

This publish step is not documented in the README or the UI, and users are easily led to assume Modules are active by default.

So I’m posting here to save others from repeating the same debugging journey.

Documentation request

It would help enormously if the documentation (README / FAQ) stated explicitly that:

• Custom Modules are source-only
• Importing into the Workbook module is the publish step
• Only the Workbook module is wired to Name Manager and the Excel grid

Even a short note would remove a major stumbling block for new users.

I’m not a GitHub user, otherwise I would also raise this there — if someone from the community is able to mirror this feedback on GitHub, that would be much appreciated.