VZD cadaster data as available at kadastrs.lv is the most current official data (it's like a day old or something like that). This is also where the addresses are imported from.

Some of their maintained data may not match, for example street lines and real streets don't a lot of the time. One has to make judgement calls on a lot of it. But 99% of the time, there won't be anything on the ground to say otherwise, so it's as good as it gets.

When choosing between cadaster data and other maps (although there actually aren't any properly-licensed ones that we can use), one should normally choose the cadaster data.

Yes, the street line data (and a bunch of other layers) aren't directly used by most other maps and services (even not shown on kadastrs.lv). Probably because of the aforementioned messy data that often doesn't match actual physical street trajectories. That custom layer had to specifically selected.
