The shortcuts in the editor are really quite poorly thought out, they've clearly been put on the buttons which have a name most similar to the function, rather than the ones that're the most easy to use.
The biggest issue is that the shortcuts to insert tables etc. are located on the right side of the keyboard, using a key (insert) that's not very often used to shortcuts. Shortcuts are typically on the left side of the keyboard because that's where your hand rests when using a mouse, assuming you're right handed. You've also selected keys up the top of the keyboard, which aren't used as much for shortcuts as it's harder to use them with the modifier keys. Typically keys up the top don't use modifiers as much (e.g. F1-F12 keys).
Next issue is you repeatedly use the same key for functions that aren't really that similar and end up with several modifiers. It's harder to press ctrl+shift+insert than it is to just press a single button. Why have you put four whole different functions on the insert key?
What is typical for designing apps like this is to just map it to character keys, this is typical across photo editors, CAD work, pcb layout software, video editing software, etc. Personally I think the keys should be something like:
a - adds table
z - adds non-identifying relationship
x - adds identifying relationship
q - adds note
Or if you want to keep them a bit more intuitive:
t - adds table
r - adds non-identifying relationship
ctrl+r - adds identifying relationship
n - adds note
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