@kat 1. I wrote about a bug in GNU Social API, when I saw an error message on your screenshot, which explains, what 140 characters include. And this is still a valid problem.
2. "5000" character limit on this instance, which AndStatus shows, is a separate case. It means that AndStatus couldn't read "textlimit" from the instance config page... This is done during "Verify credentials" of an Account of this instance. So please go to AndStatus Settings -> Accounts -> Manage existing accounts and "Reverify credentials" of the account. Maybe this will fix a problem with incorrect character limit?!