The "Max range for each inserter" setting has "incremental" and "equal" as options.

From reading the description my interpretation is that "incremental" means that yellow inserters will have 1 range + the researched range, and red inserters will have 2 range + the researched range where the inner most tiles close to the inserter are also reachable. In other words red inserters simply have 1 more/longer range than the other inserters, when just talking about vanilla inserters.

While "equal" would mean that yellow and red inserters would behave exactly the same - or in comparison to the paragraph above, the red ones would be the same as yellow ones.

However from what I can observe both "incremental" and "equal" behave the exact same way, in particular they behave how I described "equal".

Is my understanding wrong and or is there a difference between these that I am missing somewhere?

The equal range should be capped at x, so if the maximum inserter range is 3, then all the inserters will have a range of 3.

Incremental will add x to the inserter base range so that each inserter will have: base_range + increment.
So with max_range = 3
- Normal inserter will have 1+3 = 4 max range
- Long inserter will have 2+3 = 5 max range

Sorry for the late reply, I was studying for an exam and did not check the mod portal.

The fact that a programmer that worked with this mod does not understand that means that I truly fucked up with my description of the feature...
I should rephrase everything, but it's already the second time doing that... I need to take some time to think of a way to properly explain what everything does.

Edit: I will test more tomorrow after the exam but it Looks like I fucked up something else with range technologies
If range technologies are enabled, the intended behavior goes out the window and in fact (incremental = equal)... sorry, I will check better and fix this.

It's most likely an if in the wrong order.

My system to check for technologies is a bit too scattered for my taste and it's not that easy to keep consistent but that' s a problem for future me.

No worries and don't stress yourself. This isn't anything time sensitive, I was just going through SI's settings to make QAI match the new options (not sure how new they are, I just found out now :P).

As somebody who's a mod author themselves I know the feeling of getting a report about a mod, but trust me, it's nothing to stress about!