A mix of over and under extraction could be a couple of things, but IMO the most likely culprits are either inconsistency in the grind or pouring technique.
If you have a mix of really fine and coarser particles in your grounds, that'll definitely cause these problems. If you're grinding at home, you can try getting some beans ground for pourover from a café to see if your grinder has this issue.
As for ensuring your pour is giving you an even extraction; start from the centre, pouring in a spiral until you reach the edge, making sure to water all the grounds. You can also give your pourover a swirl during the brew, I tend to do one right after pouring the water for the bloom, and one after my last pour.
The mix in over- and underextracted might also come from me not stirring before drinking the coffee.
I honestly prefer not stirring the coffee afterwards. I like the slightly different notes on the first sip vs the last, but maybe I'm a weirdo.
As someone who has also spoken French their entire life; I disagree. Is French orthography messy? Sure, but it's a consistent mess. Like the other commenter said, once you know "eau" is pronounced "o", you know. Un beau bateau sur l'eau.
Contrast with English, where rough & thorough thought is required throughout tough sentences such as this one just to figure out what the Fuck sound "gh" will make.
I really came to appreciate the difference in English and French when I used to work in pharmacies; my first job was in a French place, and I intuitively knew how to pronounce drug names at first encounter.
I later worked in a place with only Anglophones and I never got the prononciation on the first try. It was a guessing game.