Economists may not studied hyperinflations much, they've spent a lot of time looking at inflation, the one economic variable public policy designed by mainstream economists is very good at predicting and influencing. They know it's the result of the amounts people are willing to spend on stuff (including labour) rising faster than the amount of stuff available. They know that government spending more money into the economy can does increase the amount people are willing to spend on stuff (but seldom 1:1) and that it can also increase (or decrease) the amount of stuff available. They know this relationship depends on how the money is spent and also on the structure of the economy and this varies over the economic cycle as well as between countries. They know people look forward with inflation expectations when setting contract prices and wage demands.
There really isn't much reason to assume inflation, a rate of change, has a stable relationship with the absolute size of the debt. It seems like the article was inspired by Rogoff and Reinhart's similar argument that a particular debt/GDP ratio was an inflection point leading to a drop in economic growth. But that paper's arguments for there being a specific amount of debt that was the problem were empirical rather than theoretical, and more importantly, were wrong (infamously the paper's main result was shown to be the result of a coding error accidentally excluding countries from their calculation)