What's today called "namespaces" in Typescript was originally called "modules" and then "inner modules" (to differentiate from "exterior modules") and is a tiny simplification on a JS pattern that was extremely common at the time of Typescript's inception called at the time "IIFE modules". "namespace" is a very C# name chosen in desperation (when it became clear that "exterior modules" were the present not just the future of the language and "interior modules" was too confusing a term to live), but it's a very old (and used to be extremely common) JS pattern that TS gave a tiny bit of syntax sugar to. It was a "standard" that existed at the time that was (rightfully) killed by AMD/UMD/CommonJS/ESM, but it is hard to fault the Typescript team at the early 0.x days thinking the "Stage Wild" JS pattern would possibly live on for many years to come. (This is also relevant to the patch notes for Typescript 5.0 as 5.0 is the first version [!] to itself be written as [proper/"exterior"] modules rather than namespaces. There are some interesting stories, including in these release notes for why that took so long to transition and what the performance benefits have been post-transition.)
Even those things that didn't seem like ES standards have some history as JS "standards". It's not like TS 0.x/1.x didn't support "standards", it is more that the TS team mostly decided to focus more on later stage ES standards (more likely to be accepted by browsers) rather than trying to "prollyfill" Stage 0 and "Stage Wild" standards.
enum is a keyword that is reserved in ECMAScript and therefore may one day clash with TypeScript. It's unlikely any ECMAScript-defined semantics for enum would match today's TypeScript enum. So it's not on any standards track.
There is already a proposal for JS enum that has different semantics to TS enum, and it was created by someone on the TypeScript team: https://github.com/rbuckton/proposal-enum
So the const form doesn't really change the hazard.
A lot was happening back in 2018. A Googler put together a proposal to add ignorable "pluggable" type annotations to JavaScript, which would allow browsers to run TypeScript directly without transpilation (and without type checking). https://github.com/samuelgoto/proposal-pluggable-types
And a member of the TypeScript team at Microsoft put together a proposal to add enums to JS. https://github.com/rbuckton/proposal-enum
Neither one of these seem to be active. What happened? What would it be like to get these landed?