optional ability to toggle static anchoring and enable inputting text for anchor positions, like top-right center-middle bottom-left (or split them into two lines, like top/right, center/middle so youd have to input only 6 instead of 9 positions) to make them easily modifiable with placeholder variables

That will not happen, sorry. If you really need "custom anchors", you can always anchor elements to other elements.
The parent element could even use advanced positioning to have a real custom anchor with full control over the anchor origin.