The build error is descriptive. FreeType2.Build.cs and HarfBuzz.Build.cs explicitly check if they are being used for a Unix server build and throw exceptions to prevent that. Commenting out those exceptions (lines FreeType2.Build.cs:145 and HarfBuzz.Build.cs:114) allows the build to proceed.
Results: The build fails with the following error:
ERROR: Unable to instantiate module 'FreeType2': Linux dedicated server is made to depend on FreeType2. We want to avoid this, please correct module dependencies.
(referenced via allmodules option -> Text3D.Build.cs)
Expected: Build should succeed.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-87878 in the post.