Why do some Bitcoin Core "good first issues" require scripted-diffs?
From the Bitcoin Core developer notes, when the bash script is included in the commit message the &quot;Travis CI job checks that the result of the script is identical to the commit.&quot; It also makes it more efficient to review for reviewers if they can review and run a bash script rather than needing to do additional checks that the PR covers all the cases it should.
With regards to the scripted-diff examples looking complicated you can look through other examples in the Bitcoin Core repo by running:
git log --grep=&quot;-BEGIN VERIFY SCRIPT-&quot;

Alternatively here is a simpler example that you can start from if you are trying to do a basic find and replace exercise.
For more information on scripted-diffs see Jon Atack's personal notes on scripted-diffs.
If you need help writing your bash script you can ask questions on #bitcoin-core-pr-reviews on IRC.