flag:type=* says that "regional" is correct to refer to states, "state" is not.

Welcome to OSM and thanks for your contribution! Informal names used only by the local community might better go in the "loc_name" tag, so that the proper name can stay in the "name" tag. Or, for the other way around, if the official name is rarely used by anyone, it can go in the "official_name" tag. Read more here: osm.wiki/Names

Hi! If you don't know the actual size and shape of a tee box, please just add a single node, rather than an imaginary circle. I've fixed the ones in this course in changeset/144804585 Thanks!

layer=* is not a physical descriptor, just a hint to the renderer for what order to draw features. Therefore it applies to the building, but not the associated amenity. It's fine to make gas stations a separate POI, but it wasn't wrong before either.

If both names are signed, it's better to list both than to arbitrarily prefer one.

To be clear, vehicle capacity alone doesn't determine the class of road. Connectivity is more important. See osm.wiki/United_States/2021_Highway_Classification_Guidance#Classification Though I don't know the specific area well so I can't say for sure whether Tantau is more or less important than Vallco or Pruneridge.

Please use the changeset description to describe what you changed and why. For example, "Added traffic light to intersection." See more examples here: osm.wiki/Good_changeset_comments

Thanks!

The restriction relation page has examples of how to use the "via" member role: osm.wiki/Relation:restriction#Members

Turn restriction relations can restrict going straight through an intersection, and can restrict specific types of vehicle: osm.wiki/Relation:restriction

If the tags on a node in a way only apply to one side or one direction, that can be indicated with a suffix on the key: osm.wiki/Forward_%26_backward,_left_%26_right

Mapping traffic signals at the way intersections is valid: highway=traffic_signals

way/1223146051 is incorrect. Only physically separate roads can be separate ways. Lanes, connectivity, and turn restrictions should use their appropriate relation types.

Please use the changeset description field to describe what you changed and why—for example, "reclassified Stanford Arboretum as a forest instead of a park." More examples here: osm.wiki/Good_changeset_comments

Thanks. The tags were added in changeset/29688748 , so you could ask the author of that change, or go to the VTA, the source they list.

Ah, I didn't know it hasn't passed yet: there's an open proposal for allowing other units in ele= osm.wiki/Proposal:Ele_with_units

The reason it's in feet is because that's what's on the sign, so it directly describes the sign; tagging with on-the-ground information is preferred over external sources.

If it's verifiable and you can't find a better tag, leave it alone, even if it's a unique tag, otherwise you're just deleting good data for no reason. See osm.wiki/Any_tags_you_like

Fixed in changeset/143180287

indoor=room is not allowed outside of a building outline.

I don't think it really makes sense for a room to be outside of a building. What are you trying to describe?

Could you put in the "sources" changeset tag where you're getting the information on these? The pipelines are tagged as being underground, and aren't visible in imagery. Thanks!