Set custom place to look for markdown files using gatsby-transformer-remark [gatsby-transformer-remark + gatsby-source-graphql]

[BrokenDuck]

Hello, I am trying to use markdown files which are available on the TakeShape CMS. I connected to the CMS using gatsby-source-graphql and it is working perfectly. I have a scheme composed out of a couple of text-lines and a markdown file. I am running into a problem, however, because gatsby-transformer-remark doesn't recognize the markdown string as markdown, and rightfully so, because in the json structuring the graphql api specifies the type of the markdown string as string :

"longerMarkdownDescription": {
  "minLength": 1,
  "type": "string",
  "description": "A longer markdown text, that decribe the feature in more detail",
  "title": "Longer markdown description",
  "@mapping": "takeshape:local:Feature.BfJ_Q5ecb"
}

I really want to use the gatsby-transformer-remark plugin as it makes you able to query the frontmatter specifically and it returns the html as a string. I can sadly not change the type of the markdown string as the json will then not be recognized by the CMS. Is there any way I can specify to the plugin-transformer-remark to look specifically for these strings ? Please tell me if any other information is required !