Filter by Custom Fields and/or resolve Custom Fields for searching

In RDM for my filter options within the navigation pane, I have basically everything checked so that it will filter through whatever information I have in my connections (i.e. URL/Host/IP/Domain). My typical connections will start with an RDP entry and then have sub connections for what relates to that server, typically Web Browser entries. To avoid duplication, I always use parent variables within the sub-connection entries since they typically all rely on the same website domain, just a different path. I will store that common domain variable on the parent RDP entry within a custom field. MOST connections are set up in this way, and sometimes with slightly different custom field usage (i.e. breaking out domain, HTTP vs HTTPS, URL path, etc). Below is a screenshot of what my typical connection setup is composed of:



Anyhow, I have a need to use the RDM URL Protocol Handler (rdm://open?Filter=$SEARCH$) from an external application to open RDM for one of these parent/sub-connection nodes. The one thing I can currently count on being the same between the two systems is the URL/domain. However Taking the URL protocol out of it, and just doing a normal filter search, I am NOT able to resolve any connections (parent or otherwise) where the search value I'm looking for is resolved by custom fields (i.e. $PARENT_CUSTOM_FIELD1$) or where it is contained within the custom fields of a connection entry.

So I either need a way to 1) Search through custom fields, 2) Search through fields that contain connection variables, or alternatively 3) see if the URL protocol can be used in another way to get my desired results.

The quick & dirty fix is to either replace all variables with hardcoded variables and/or just add what I intend to search for as raw text in the description field or some other searchable field, neither of which are desirable or practical.

P.S. Do y'all have a live version of the RDM URL protocol handler documentation? Looking at this blog post, the below URL referenced does not seem to work anymore:

https://help.remotedesktopmanager.com/support_protocolhandler.html