Hello Arthur,
Hm... do not know exaclty what you mean.
HE currently reacts on extenrally chnaged files by default and brings a popup. Then you can decide, Update, Not Update, Always Update, Never Update (this
Always settings can be later changed in Files Menu,
Auto-Reload).
In addition you can create special syntax schema, inherited from Plain text (txt_spec.xml) and add aditional styles for error:, warning: etc... If you like you can check
Overview Bar in syntax definition Fonts & Colors for your style, to show it in overview bar.
But there is no something like Beep or Flash

when something is found in document on loading.
Maybe this is useful feature, but rather specific. I would put it in my to do, but dont know when I can check for something like this.
In addition I can think to show such styles in addtional panel (as output). It is already can be useful for showing of the TODOs from code...