I know that midi doesnt have much strict rules but a begginer would expect A4 to be 440hz because almost every tutorial, video etc. says it is.
But in renoise, a4 represents what is elsewhere usually a3 (so a4 is 220hz as you can see in spectrum viewer in beta6).
I understand that it can not be changed right now or can if old tracks would be automatically transposed (but it would confuse every old renoiser, so i dont suggest it).
But i am courious why is it? Is it just decision from times when midi things werent so standardized or is there some deeper reason? Thanks 
That is not something Renoise can decide. It depends entirely on the samples you use and the basenote you set it to.
You can perfectly well put a 440hz pitched sample and set it’s basenote to A4 and then you have the correct octave on the correct key.
Have you tried already beta 6?
There are notes showed in spectrum analyzer and when you point at 440hz it will show a5.
In melda equalizer and other plugins that show notes according to frequency 440 is usually a4 (like in tutorials etc.)
But it is not any new. Most of the other daw have middle c on c3, renoise has it on c4 (tested with vsti).
Renoise also starts with C-0 where most other daw’s start with C-1. I’m not sure how many DAW’s there are that support 10 octaves, but if you do support it, then middle C supposedly has to be somewhere in the middle 
.
My bad, should have read more closely. Midi is not my area.
Vv: Yeah, it looks like most logical reason. Thanks
I’d also prefer 440Hz on A4. Maybe there could be a setting in the preferences to use the standard A4=440Hz or the Renoise A5=440Hz!?
Also A3 = 440 Hz, C tuner (VST) uses this.
Different DAWS use different octave notations. Some start at -2, some at -1 some at 0. We have a good reason to start at C-0, because we else would need an extra digit for +/- in the pattern editor to to type in values like C#.-1 (minus one).