Thank you for all the information!
As I live in Europe, the exact brands will likely not be found here, but I will definitely look up some comparable alternatives for future endeavours
I might experiment with epsom salt and crushed egg shell mixtures on my other chilies first and see how they like this boost in Ca and Mg. The fertilization of the reapers will be put on hold until the current flowers either start fruiting, or in the worst case drop off again, so I can respectively not change or change tactics when the next flowers start to blossom.