herolulu Hmm, I checked the Spine project, but I can offset the zuoxiaobi bone's timeline and the mesh shapes seen in the viewport seem to match at frame 0 and at the last frame, so I'm not sure what the problem is. If you have sorted out the constraints so that it works, could you please show me the project where the problem occurs?

By the way, if you send us a Spine project that is too complicated, it tends to be unclear where to look, so it would be helpful if you could send us a project with only the parts that cause problems and remove the rest.

herolulu Thanks for submitting the simplified Spine project! It seems that the rotation keys for bone84, bone85 and bone86 do not match in frame 0 and the last frame:

Did you filter the rotation timeline? When you filter the timeline of a particular transformation in the Dopesheet or Graph view, you may think you have selected all the keys, but you have not. If you can think of any reason for this confusion, please let us know for our reference.

herolulu Hmm, that's weird. As far as I have tested, I have been able to match the rotation values of the first and last keys by copying and pasting the keys:

So I am not sure what the actual cause of the problem is. However, I noticed that while the offset button is enabled, even if you select the white key in the overview row, you cannot select the keys in all the timelines of the same frame, so I thought that might be the reason why you thought you had selected all the keys, but actually hadn't:

In the video above, you can see that when the offset button is disabled, selecting the white key in the overview row selects keys in all rows, but when it is enabled, only the key of the top bone is selected. This has always been the case, so it's not a bug, it's design, but I thought it might cause confusion when trying to copy keys.

Could you please try again to see if you can copy and paste the keys correctly?

herolulu Hmm, I'm not sure I fully understand the content of your question, but is it correct to say that you are asking where you can check the correct scale when importing a skeleton that has been exported once? If the skeleton's texture was scaled when exporting, the scale information is saved in the atlas file.

If you set the scale based on this value when importing the skeleton data, you can set the correct size for all the attachments at once without having to manually modify the size of each attachment:

The following blog post, which explains how to import skeleton data, also explains this, so you may find it helpful:
Blog 导入骨架数据 #疑难解答 - 为何有些部分比正确尺寸小或大？