You've answered with your options. Either click and edit each individual annotation or open with your favorite text editor and be prepared to write XML safe comments i.e.
runs when sales_amount > 30
Now that I have cracked open a 2017 version SSIS Package, the annotation XML is far friendlier for text editing than it was in the 2005/2008 era.
Given a package that looks like
Inner Annotation > 30 is out in the "clear" down in the DTS:DesignTimeProperties in a CDATA field. Update all the Text attributes, save and reopen and you should be good.
Text="Inner Annotation > 30"
Normally, I'd put a plug in for Biml as you can reverse engineer a package to a simplified XML markup, edit there and re-generate your SSIS package.
This is what the above package would look like (assuming I imported the SSIS Annotations which is not a default)
<Package Name="dba_288939" Language="None" ConstraintMode="LinearOnCompletion">
<Container Name="SEQC Placeholder" ConstraintMode="LinearOnCompletion">
<Annotation AnnotationType="Description">Sequence Container</Annotation>
<Dataflow Name="Data Flow Task">
<Annotation AnnotationType="Description">Data Flow Task</Annotation>
However, the emitted SSIS package doesn't have annotations in it. I'll reach out to the fine folks as Varigence and see what I'm doing wrong in the package generation phase.
Visual Studio 2019 annotation edit experience