Sure update the code can solve the problem. 
And I located the bug which cause the problem:

1, when Odoo generate the tranlsation term to file  , it trim the space ending.

2, And Odoo can't find the matched term as the non-trim term can't be found .

How to fix:

Following the commit in this url

https://github.com/odoo/owl/commit/f54b9a4a0cbdd5bb6088b15218e73d5b4a9731c8

You can locate the code in file addons/web/static/lib/owl/owl.js

Same issue and don't find anything.
Tried to add a translation on the fileds located on web/src/components/chatter_topbar/chatter_topbar.xml with no success.

It's very annoying and generate a risk for user to send accidental an internal message to the customer. 

If anyone has the solution, I would appreciate :-)