Hello @Davii, welcome in our community.
First of all, there is a distinction between the Xm_[successful,redirects,w/e] group of alerts and the ones with the web_log_ prefix. The first ones are managed from the python.d.plugin collectors and the second ones from the go.d.plugin. One of these plugins is running at the time for web log analysis. So whatever changes you have to do, must be focused on the go.d.plugin collectors.
The most recent and related to your problem thread/topic/issue is this Why does web_log_1m_successful count redirects as failure? and how to change it one, in which we explain how we define the classes of the responses code. In your case, and since this is a private RPi you can assume that the 301 codes as successful.
Best regards,
Tasos.