The ability to configure the country code.
It’s very useful to set main grids Hz and Voltage values automativally to discovery and polling routines without manual configuring. Of cource the should be ability to change it manually if device is outside of the country code. Also there could be better to add possibility to set the “feeding system” like AC/DC.
Why:
Quite often everything works like a charm. And suddenly we have power loss. So the aggregate starts to feed UPS. Everything seems to work nice and calm and then aggregate gets too much old fuel and rotation speed starts to dance. Noe the UPS is feeded electricity made by Devil and if there is no alert values the UPS will die soon or later.
Lightning strike destroys one of the phases of power line and UPS gets too weak power so batteries starts to drain and we don’t know that one phase is missing.
Neighbour is stealing power for his cannabis plant. No ups at all and power voltages are always under limits so your fridge, computer, tv and air condition are soon totally broken.
Quite often the main reason of broken device is bad electricity. Actually I think it’s quite easy to make country detailed power alert measures for millions of devices. Conclusion of mine. If something is standard ruled by law there is no reason why everyone have to make those king of rules by hand because automation can make it much easier and without wrong spelling or misunderstanding.
What we know in example like this:
Country: Finland
230/398 volts +10% - 6% (ie. between 216.2 volts and 253 volts)
50Hz ± 1% (ie. between 49Hz and 51Hz)
- AC system (Typical for ie computers and servers)
- Voltage high limit = 253 volts
- Voltage low limit = 216,2 volts
- Frequency high limit = 51Hz
- Frequency low limit = 49Hz
- DC system (Typical for telecommunication, core routers, some datacenter servers and environment analytic devices)
- Most used voltage 48 (low limit 44 volts and high limit 52 volts
- Some vendors like Ubiquiti uses 24 volt POE system
Country: Taiwan
110V/60Hz
Country: Morocco
127V/50Hz
220V/50Hz
Country: Liberia
120V/60Hz
240V/50Hz
As we all can see we have quite much variation between countries and quite often the most of people are not sot experienced that they can change those values easily so we can help a lot if values are set by default. 
Just one problem… Perhaps some LireNMS architect can implement this feature because I suppose that my LibreNMS knowledge is too weak to make this clever way. 
I can collect the data of main grids. 
Actually I have not seen this feature nowhere yet.