Is the following a correct interpretation?

WikispeechHook#onParserAfterTidy is the only thing referencing HTMLGenerator, but since there is no ParserAfterTidy registered in our manifest we can simply delete HTMLGenerator and remove WikispeechHook#onParserAfterTidy without further delay.

Or am I missing something defined in JS, or perhaps something we extend from the extension library which execute the hook?

That is correct.

The first implementation stored utterances as HTML elements when rendering the page. This is now handled with Ajax in the Javascript modules (specifically Storage).

Change 573523 had a related patch set uploaded (by Karl Wettin (WMSE); owner: Karl Wettin (WMSE)):
[mediawiki/extensions/Wikispeech@master] Wikispeech: Remove HtmlGenerator

https://gerrit.wikimedia.org/r/573523

The last two days I've been getting a lot of

kalle@musa:~/projekt/wikimedia/Wikispeech$ git review -R
You are about to submit multiple commits. This is expected if you are
submitting a commit that is dependent on one or more in-review
commits, or if you are submitting multiple self-contained but
dependent changes. Otherwise you should consider squashing your
changes into one commit before submitting (for indivisible changes) or
submitting from separate branches (for independent changes).

The outstanding commits are:

5e0cd09 (HEAD -> T244344) Wikispeech: Remove HtmlGenerator
e3a81dd (T243376) Merge remote-tracking branch 'origin/master' into T243376
a55bb35 Bump manifest version up from 1 to 2

Do you really want to submit the above commits?
Type 'yes' to confirm, other to cancel: yes

This is all good, right? This is due to the other tickets sent to review that has not yet been +2:ed? Or do I have a messed up local repo?

Change 573569 had a related patch set uploaded (by Karl Wettin (WMSE); owner: Karl Wettin (WMSE)):
[mediawiki/extensions/Wikispeech@master] Wikispeech: Remove HtmlGenerator

https://gerrit.wikimedia.org/r/573569

Change 573523 abandoned by Karl Wettin (WMSE):
Wikispeech: Remove HtmlGenerator

Reason:
I messed up the branching, starting over from scratch.

https://gerrit.wikimedia.org/r/573523

Change 573572 had a related patch set uploaded (by Karl Wettin (WMSE); owner: Karl Wettin (WMSE)):
[mediawiki/extensions/Wikispeech@master] Wikispeech: Remove use of Utils.php

https://gerrit.wikimedia.org/r/573572

The change above is not related to this task. It should be https://gerrit.wikimedia.org/r/573569.

Mentioned in SAL (#wikimedia-cloud) [2020-04-07T08:34:28Z] <wm-bot> <sebastian-berlin-wmse> !log wikispeech Deploy latest from Git master: 85fa89a (T244344, T244345), f79fe03, 956e507, 66da277, 18c20c7 (T246085), 044eba0 (T249207), 2f98bef (T203161), 7aa7556 (T245823), 43e26a2