I return to the legend problem and an post I made about 2 years ago. The problems are is now a bit different, but of the same kind - that means legend customisation:
I see no option at all to change the size of the polygon and line items in the legend - that means the first column in the tab, what shows a) the filled box for polygons or b) the wave line
In the result, the difference in size between point items and polygon/line items in the legend is sometimes quite large.
Second: I see no option to reduce the height for an legend item. I can increase the distance between the different items in a workaround by creating an empty entry but I see no chance at all to get the items closer to each other.
But perhaps there is a workaround also for this problem
The way I make complex legend layouts is like a normal map, and then in the template assign that legend.geo to the template furniture box "Map Maker Project *.geo". (see my reply to one of your other questions).