Hello.
I don't think it's correct to create multi-polygon relation into "traffic islands". The way you mapped them, semantically inside areas become NOT "traffic islands". It is perfectly sufficient to map one area inside of another without creating a relation out of them.

Also I'm not even sure all those areas are correct to map as "traffic islands". They do not match the description as documented in https://wiki.openstreetmap.org/wiki/Tag:traffic_calming%3Disland
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            Published using OSMCha: https://osmcha.org/changesets/133921640
            