Btw. just came across your FOSDEM talk (https://fosdem.org/2021/schedule/event/new_type_of_computer/) which I found very interesting. Modula-2 was actually inspired by Mesa, not by Cedar (see https://dl.acm.org/doi/10.1145/1238844.1238847), and you might also be interested in this paper (concerning the implementation language of the ST VMs): https://dl.acm.org/doi/10.1145/3386335. Btw. a lot of good ideas from ST went into Ruby and finally Crystal which might be an adequate alternative solution for your two language (Oberon & Squeak) approach.

Thx