How to reproduce:
Thank you for reporting this problem, I will investigate.
I've realised the issue is not the characters but the number of characters entered. beorg only performs the search is 3 or more characters are entered. This minimum length isn't helpful for languages such as Chinese. What I'm going to do is add a setting so a user can change this. The reason for the setting is performance when searching using the UI. You'll see this new setting in the next update.
Seems that there is still no such option in version 2.15.0(129)
This is a setting that needs to be added to your init.org - for example
(set! filter-min-chars 2)
If you aren't familiar with using an init.org for advanced configuration of beorg please review https://beorg.app/learning/excluding-tasks-from-specific-files-for-the-agenda-and-todo-lists/
Make sure you restart beorg (i.e. kill and the start again) for the changes in the init.org to take effect.
Can you provide a screenshot showing the search, and a sample org file so I can reproduce the issue?
Thank you for sending through the example. I'll investigate this further over the next couple of days and let you know if either there is a bug (which can then be fixed) or if a beorg configuration issue.
I've just tried reproducing this however it is working for me. I have switched between my init.org setting filter-min-chars to 3 and 2, and can see the search not working (on 3 characters) and working (on 2 characters).
Potentially this might be a syntax error in your init.org which is causing beorg to fail to read the configuration you've added. Check the beorg log to see if there are any errors. Alternatively try temporarily removing everything else from your beorg init.org except the filter-min-chars section and see if that fixes it, and then try and work out where the error is.
Failing the above try sending me the whole init.org and I'll see if I can see an issue.