Craft 3 - Twig search query for entry with custom EntriesField containing disabled entry
The search parameter only searches the element that is the subject of your element query (i.e., the source entry) - it does not search related entries. For that you need to use the relatedTo parameter. (I'm not sure why you're getting a successful result for the November entry - perhaps the source entry also has the word November in it somewhere?).
Additionally, you'll need to use the anyStatus parameter to fetch expired entries.
So to pull this off, you'll need to conduct the search against the other section and then find related entries, i.e.:
{% set sectionBEntryIds = craft.entries.section('SECTION-B').search(searchParam).anyStatus().orderBy('score').ids() %}

{% set sectionAEntries = craft.entries.section('SECTION-A').relatedTo(sectionBEntryIds).all() %}