Hi @tobiasspaeth83 and @machadoa953
A big welcome to the Bubble Community @tobiasspaeth83 - I understand this was your first post. Looks like you’ve jumped in at the deep end 
Sorry for the pause, I need to take a deep breath every time I return to Google’s API 
In answer to your question:
My understanding of Sheets API is that it returns a ‘chain of values’, exactly as you described, either as a row (majorDimension=ROWS) or a column (majorDimension=COLUMNS) of cell values. Either way, data returned in your GET request isn’t in the nice JSON format you and I were hoping for. Or not how I understand the API - I am happy to be corrected.
My ‘solution’ was to pull in each value from the string of values into a separate cell in a repeating group. You can read more details about that solution here: Mastering Google Sheets API - #10 by aestela
But I’m reluctant to even call it a solution because it only half solved my own problem. And before I had the chance to find a better solution, my employer moved to Excel so I left it unfinished.
In short, I’m not the best person to ask, sorry!