We're seeing the following behavior with importing from courses into courses created prior to upgrading to Moodle 4.4 and the change from "Topics" to "Custom Sections". Let's say Course A has customized section names as follows:

1. Section 0: "Summary of course"
2. Section 1: "Readings"
3. Section 2: "Assignments"

Now, let's say we're importing into Course B. Course B was created prior to upgrading the environment to Moodle 4.4. It has the following section names:

1. Section 0: "General"
2. Section 1: "Topic 1"
3. Section 2: "Topic 2"

These are the default section names for the pre-Moodle 4.4 topics course format. They haven't been customized. When I import Course A into Course B, I expect the following section names:

1. Section 0: "Summary of course"
2. Section 1: "Readings"
3. Section 2: "Assignments"

This is what actually happens:

1. Section 0: "Summary of course"
2. Section 1: "Topic 1"
3. Section 2: "Topic 2"

I haven't done a thorough code review; I assume what's happening is that "Topic 1" and "Topic 2" are treated as customized section names and therefore aren't overwritten.