Unfortunately this problems is entirely caused by the Huawei firmware. Every time a launcher is updated the choice of your default launcher is reset. If you have 10 launchers installed, you will have your choice reset very, very often.
Also the choice is reset even if the current launcher is closed in a way that the system consider anomalous.
We cannot do anything to fix this issue, our best suggestion is to uninstall launchers that you don't use and to use some patience :-(
You should completely ignore that message, it’s just an attempt by the system to convince you to come back to the built-in launcher. That message appears after a simple crash or a freeze not necessarily caused by Smart Launcher itself. There is absolutely nothing to worry about it.
Unfortunately Huawei is known to block the launcher selection on some devices, appearantly only those imported from China.
You can read more here:
Sometimes, device manufacturers, limit some features to work only with their own apps. This happens especially with quick dial shortcuts. Unfortunately, Smart Launcher can’t circumvent this limit. Our suggestion is to install and use a different app to add the kind of shortcut.
At the moment, there aren’t any other known issues on Huawei/Honor devices, if you find any, please report the problem to firstname.lastname@example.org