Deno Support?
No such current plans exist. The source files include .js extensions when importing TypeScript files; is that still unsupported in Deno?
Not sure I understand, does this project contain TS in .js files? Or do you explicitly import from a non-existing .js file but actually mean to import from the corresponding .ts file?
Deno's imports are URL-based so it can fetch any file as long as the path exists or the path can be resolved using the import map. I believe it uses the file extension for language detection on local filesystems, so it will error if you import a .js file, but it's actually written in TypeScript. For online registries and CDNs the server is mainly responsible for handling module resolution, content type, and type acquisition.
For Fluent itself, @fluent/bundle is available through https://esm.sh/@fluent/bundle@<version> (I haven't checked if all the other packages are on it yet). Deno's npm import feature should also work fine, although it wouldn't be my first choice.
In any case, I think this issue can probably be closed since the CDN import seems to be working fine.