Thank you for the details, I will try to answer everything the best way I can.
1. Search content and child posts
If I understand correctly, the parent posts only contain a shortcode, which displays the actual content, which is gathered from various child elements. I believe the Index Table engine feature might be able to do the trick for you. It is a secondary engine, which requires building an index, but it's capable of reading most executed shortcode contents.
Please read the following chapters in the documentation carefully, on how to generate and use it:
– What is the index table?
– Generating the index table
– Enabling the index table
2. Filtering by formula
This is a much more complicated issue, I recall someone already asked something similar, and the conclusion was that it's not possible, without extensive modifications to the code.
The built in filters interact with the database directly, for the maximum performance. This works well with any statical value, where you can apply an equasion, bigger or smaller or a between operator. Calculacting distance however is much more complicated, and the fundamental problem is that it is always relative to something – and it's usually given by two coordinates.Best,
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