No problems at all Jack. You didn't sound harsh at all.

There isn't a single "best practice guideline", but the wiki has a good explanation of lane tagging: https://wiki.openstreetmap.org/wiki/Lanes.

It is widely accepted that highways should not be drawn separately where there is no physical separation. Instead, the lanes:, and change: keys are used to define the features of the road. (JOSM has a plugin that visualises these tags, for eg, https://imgur.com/a/7pc96W6)

There is no hard-set rule determining how the split should be drawn though. I've used a literal interpretation, but as TheSwavu points out though, there is another way to draw this turn lane while still adhering to the "no physical separation" guide. I'll make some adjustments to the intersection and see how that turns out.