My condolences.
I never had to program any of that, so can't speak to that side of it, but where I worked we used Notes to quickly build a lot of internal forms and workflows, and had some internal discussion forums and documentation in it, it all worked pretty well as I recall.
The one weird thing was we had to run it on OS/2. The only OS/2 machine in the server room.
We didn't use it for email though.
Maybe I'd have a different opinion now, but I remember it working pretty well for that purpose back then.
At my previous job they had been using Notes since the company was founded in the early 90’s, meaning they lived through it being Lotus Notes, then IBM Notes and now HCL Notes.
Everything was deeply entrenched - email, warehouse inventory, ERP system, all documentation made in the entire company… just everything.
And this is for a scandinavian company manufacturing high tech devices for telecom and aviation, among other things.
It was… an interesting nightmare, constantly got in the way of any sort of productivity. Definitely contributed to me leaving early
I didn’t use notes much, but it was a platform ahead of its time, that thanks to IBM’s… IBM-ness was ignored and allowed to rot.