Sounds fun! Feel free to take a look at this demo (and the other ones in the same folder).

That REST API is indeed for querying iFind indices (hence the direct reference to an index you can provide) and the somewhat confusingly named "query" argument is actually to pass in the iFind search string. The API will then build a full SQL query for you and run it right away. 

Here's the OpenAPI spec for this endpoint (from self-documentation endpoint /api/iKnow/v1/USER/swagger):

  /table/{table}/search:
    post:
      operationId: /table/{table}/search-POST
      summary: |
        Search the given iFind index in the given table
      tags: ["iFind"]
      parameters:
        - $ref: '#/parameters/tableParam'
        - name: RequestBody
          description: JSON object with a list of query-specific arguments
          in: body
          schema:
            type: object
            properties:
              query:
                description: This is the only necessary parameter with no default value. The search terms to query against the iFind index.
                type: string
              index:
                description: the iFind index would be searched against, if you don't specify it, the first found iFind index would be used .
                type: string
              option:
                $ref: '#/definitions/OptionSpec'
              distance:
                description: only valid when option is fuzzy search (when option is 3)
                type: string
                example: "3"
              language:
                description: iKnow-supported language model to apply, for example "en"
                type: string
              includeText:
                description: whether the returned columns should include the column beging indexed by 'index'
                type: integer
                default: 0
                enum: [0, 1] 
              columns:
                description: specify the columns which also needed to be returned. For example, ["column1","column2"] 
                type: array
                example: []
                items:
                  type: string
              highlightSpec:
                $ref: '#/definitions/HighlightSpec'
                description: the parameters needed for Highlight
              rankSpec:
                $ref: '#/definitions/RankSpec'
                description: the parameters needed for Rank
              where:
                description: the valid SQL logical condition statement. For example, "column1 = ? AND column2 = ?"
                type: string
      responses:
        200:
          description: Successful response
          schema:
            type: object
            properties:
              rows:
                type: array
                default: []
                items:
                  type: object

Indeed, and very applicable too as iFind was created in Belgium, pretty much where the little Asterix village is located 🙃

Love it @Luis Angel Pérez Ramos !!