The preparations of all submodules are submitted too and I started the first I-build:

• https://ci.eclipse.org/releng/job/Builds/job/I-build-4.38/1/

To summarise this preparation: As far as I can tell, all already automated preparation worked well. But still a few more tasks that could be automated, too.
Besides the other tasks listed in #3264 and performed/checked manually:

• Clean forceQualifierUpdate files for doc bundles
  --> Implemented in:
  • [RelEng] Clean doc-bundle qualifierUpdate files in release preparation #3279
• Splash Screen
  --> Implemented in:
  • [RelEng] Add release preparation script to update the Splash-screen eclipse.platform#2139
• Update build calendar for platform release

the following tasks were noticed during the preparation and should also be automated:

• Clean forceQualifierUpdate files for PDE doc bundle:
  Prepare 4.38 development eclipse-pde/eclipse.pde#1948 (comment)
  --> Implemented in:
  • [RelEng] Add individual release preparation script for PDE eclipse-pde/eclipse.pde#1951
• Enforce qualifier update for org.eclipse.help.webapp:
  Prepare 4.38 development eclipse.platform#2134 (comment)
  --> Implemented in:
  • [RelEng] Update qualifier of o.e.help.webapp during release preparation eclipse.platform#2153
• Enable early redirection in Oomph setup:
  Update the platform setup to redirect 4.36 to 4.37 and 4.37 to 4.38 #3274
  • Turning the redirection off could be automated too as part of promoting the final GA release build.
• Investigate and if possible, fix build failure of jdt.core after release preparation:
  Prepare 4.38 development eclipse-jdt/eclipse.jdt.core#4364 (comment)

Maybe automatically removing unused API-filters could also be something that would be interesting to automate. OTOH,