Die Herausforderungen des Sprachenlernens als Erwachsener

I opted out of learning all grammar until I able to read freely. You don’t need rules to read, and you learn complicated corner cases (when grammar matter) one by one, and get intuition.

Then you discuss with a teacher proper rules to support intuition.

Not a fast way, but low stress and pretty yielding in the process. When you can read (and can understand), Greek becoming less and less intimidating.

And for ‘can read’ you need:

1. Learn all new words you find in the text.
2. Try to recover dictionary form of the word from declination (ChatGPT is really good at it)
3. Occasionally ask questions for grammar, when meaning is not clear.

The rest is simple: read.

Recently I’ve added also videos with greek subtitles to help with listening skill, but mostly the same reading, but at higher speed.

That seems kinda an ineffective way to learn language… You seem to be overdoing the grammar aspects, you don’t need that unless you’re an academic. Think about learning a language as a baby learns it.