We only finished our data tool around 2019, and then it took time to learn how to use it with the different data structures for each component of DP (I would say I currently only really know about 30% of the data structures in the game). Each data set has it's own structure and quirks, and some are more complicated than others.
Working and changing things on DP is a very slow process; the game was not really designed in a way that allows for easy or quick development, and much of the game was designed specifically to not be expandable easily. Dragon families are a good example of this, where Dragon families are hardcoded in such a way that there are very few differences, and there is no real way to change or expand on those differences. Bonuses, stats, evolution skills and a few other things are about all the game supports, and expanding that would require completely rewriting the systems in place.
The same goes for a lot of in-game mechanics or systems, where the foundation of those are very difficult to expand or adjust without just having to rewrite the game entirely.
About 60% of the development of DP is having to learn how things are done, why things are done and how to work within the limitations. The last 40% is split between crying and curling into a fetal position for the first 60%, and the remaining 20% is working through tears to try to make changes and fixing things as we can.