you can upload the backup to some cloud drive like onedrive or google drive or mega.nz and send me the link in private message.

Btw. as i written before about the regional item which of i have cancel the trade offer and it disappears, i have log into game today and i have it in my inventory (just like when you add item to the player from livemap - not through RCON). Is this expected behaviour or not?

No, but let's look at one issue at a time.

Thanks for providing the server backup. That was helpful getting a better idea of what could be the issue.
Can you please replace this attached mod file on your server, and after a server restart check if it solved the teleporting? Thanks

So, on foot, the teleporation does not happens, player avatar just got root and invulnerability effect. I tried it on the horseback as well, in this case i was teleported to the trading post roof (also was rooted and made invulnerable).

Looks ok, just the horseback case need to be solved (maybe the case where player is on horse cart may trigger the teleport as well).

I had some fun with the horse case, that seemed to be really tricky. I've made another version of the transfer file (see attachment) that you can try. It'll try to force dismount the player and wait some milliseconds to make sure the player has correct position assigned before the respawn happens.

I'm not happy with this solution though tbh. Maybe will just force dismount the player when the trading window is opened with the next client mod update.

Feel free to try this one.

Hi, i will try this new version soon. I have not time to play for last two days, now i must wait to until the server will be empty, i don't want to kick players off just to install this new file.

I can confirm that your last changes works. Good work!

Thanks for the feedback. I'll incorporate these changes in the next update.
(in the meantime anyone with the same issue feel free to use this file as a hotfix)