One thing that might be nice to do is to include an entirely WGS84 transformed version of the data for people looking to perform worldwide geospatial analysis. if the datum/projections are available for the regional datasets it’s a relatively trivial program to write as part of the ETL processing needed to make data available (PROJ implementations such as proj4j have everything you need to do this if the input metadata is available). Might need a decent amount of compute to perform all that transformation on a regular basis, but if it’s something like a weekly dump it doesn’t seem unrealistic at all. I think an optimized Spark job using proj4j on worldwide OSM data could probably perform this task in a few hours.