Thanks very much for your work on this! Assuming that 2-Butoxyethanol ("2BE") is the culprit, there were two things that jumped out at me from the Ministry of Environment fact sheet: first that the restriction on 2BE appears to have been in place since 2007 -- so not a new issue by any means. Second, more importantly, the Minister has the power to grant an exemption permitting the import of a product which contains more 2BE than what is allowed under the regulation.
So, with luck, there appear to multiple possible pathways forward (reformulation by Tamiya if necessary, or an exemption order by the Minister). It's even possible, I suppose, that if Tamiya spray cans used to have higher concentrations of 2BE than they do now, and an out-of-date MDS describing the old formulation was submitted by the importer, that the current Tamiya spray cans are actually compliant, and it's just documentation issue that needs to be resolved. Fingers crossed.