incorrect mirroring when copy pasting keyframes, transitions between poses incorrectly

Can someone please help me out with a problem I have regarding keyframes and inbetweens in Blender? This is my first time animating in Blender really so I’ve got zero experience.

I‘m animating a walk cycle - I copied all keys from frame 1 to 12 and pasted them to frame 16-32 and flipped them (clicked the button „copy pose“ after selecting the whole model and then „paste x flipped pose“) to achieve a loop. The issue is that some inbetweens are not exactly mirrored. For instance: the model on frame 17 should be in the exact same position as frame 1, just flipped. But that’s not the case here (see video)

I tried deleting every keyframes after frame 12 and pasted them all again but it doesn’t change anything. I know now that it has something to do with the graph editor (interpolation etc.) but Id like to avoid changing the mirrored graph manually… how can I mirror the graphs perfectly?

what I found online but it didnt help:

One way to make every inbetweens align is to copy paste every inbetween but I’m pretty sure that’s not the right way to do it bc it’s gonna make the whole process unnecessary complicated, especially when you change the keys again?

Please help! Explanations for dummies are very appreciated.I can also provide the blend file if necessary.A link to a screen recording is attached! click here

Welcome!

You vastly overestimate how nice 3d tools for animations are, lol. Sometimes it is just that tedious.

To make the process more brainless you could keep the action you have now for editing then once you want to see it finished you can bake it, copy all the keyframes from the first half of the cycle, then paste those keyframes flipped in the action editor. You could also make some quick favorites or macros to speed up the process