The z-offset value is applied after probing – in fact the main purpose is to offset the “contact point” (washers) toward the actual bed surface.
You should be able to change Z-offset via the LCD, or via gcode M851 / M500 commands. Use small adjustments to find what works best. If your current value is -1.215, I would suggest -1.220 or -1.225 for your first test. A small difference (.05-.10) can make a BIG difference, so try a little bit at a time and test print to see the effect.
The auto-leveling will never be absolutely “perfect” across the entire bed for a variety of reasons. But the larger first layer height (0.425 is default in the CuraLE profiles) coupled with a little “squish” from the Z-offset helps obscure any minor leveling issue. The thinner that first layer, the more likely you are to see ill effects from any slight leveling or Z-offset inaccuracy.
As for the 0.5 nozzle and small details… Different slicers will treat this differently, but some slicers will just ignore small features like lines that are less than the nozzle width. In general, for that fine detail you do need a smaller nozzle. You can sometimes overcome this by setting the nozzle size to 0.4 in the slicer – which will then render the features, but in actually printing will extrude 0.4mm worth of plastic out of the 0.5mm orifice – meaning it will print the features, but they will be wider and under-extruded. Depending on the model and what you are trying to achieve, that may or may not be acceptable.