I would guess java was chosen for its high quality libraries, efficient runtime and its static typing, which enables easy and safe refactoring.

Exactly this.

We find modern Java to be ubiquitous, fast, and (still) super popular in enterprise environments.

Salesforce is customized in something called Apex, which is a dialect of Java. Would make migration/integration more convenient

Its like Java 5 mashed with some C# and then they've added their own syntax changes on top for custom salesforce things.

Yes, I haven't used this myself yet but I have been keeping my eye on this project for a while now, https://erpnext.com/ The Frappe framework that is the foundation of ERP Next can be used to extend the ERP platform or build standalone apps.

[Odoo is Python based](https://github.com/odoo/odoo) and the 'core' modules are open -

Not providing any endorsement of the software nor can I say how the Odoo CRM/CMS compares to Salesforce. I've tried migrating a non Salesforce business to Odoo twice and haven't had success yet.

Python is significantly more resource heavy than Java. This is not a notebook or quick script. What would Python offer here?

Objectively, very little probably. Non-java shops tend to avoid it because java codebases have a reputation for being relatively complicated. Java is a great language though and it may very well be the best cultural fit for the type of org that _actually likes_ salesforce. They also seem to be publishing a docker image, so it shouldn't be difficult for non-java orgs to integrate.

Python is more resource heavy than Java for CPU, but not for memory. I am pretty sure that Java is more resource heavy for memory.

Also, Java programmers have the habit of using excessive abstractions that don't solve real problems.

probably because java owns the enterprise space.

I can recommend https://github.com/frappe/frappe as a general engine, https://github.com/frappe/erpnext is a full blown CRM/ERP built on top of it