The most important thing to remember is this:
This judgement agrees with the ECtHR judgment in AP, Garçon and Nicot v France
(2017) (App Nos 79885/12, 52471/13 and 52596/13), that a medical diagnosis is a reasonable requirement for a state to impose before granting a legal change of sex because it can legitimately balance other interests against that of transgender individuals.
The court has therefore rejected self-id as an option.
In accordance with shifting terminology in the medical profession however, the court did find that while evidence of a diagnosis can remain a requirement for a GRC, the condition diagnosed should no longer be referred to as a disorder.
There are various ways of achieving this and it depends on what the court finds is the remedy for the current terminology. It may not change much at all, it may change a lot. There is a large amount of overlap between the diagnosis preferred by the applicant (gender incongruence) and the diagnosis that is currently required (gender dysphoria). The main difference is the absence of serious distress which is present in the latter and absent in the former. In practice though, both diagnoses may be seen as as good as the same.
Please also not what the court states in [151] (p.51f.) in rejecting the applicant's claim that being treated differently from a woman in having to prove gender dysphoria before being recognised as a woman by the state is unlawful discrimination (a violation of Article 14 rights under the European Human Rights Convention).
^"I am not persuaded that she is in an
analogous position to her comparator, namely a non-transgender (or cisgender)
woman; and, in any event, would consider the difference in treatment between the
two to be objectively justified – whether one applies the manifestly without
reasonable foundation or the fair balance level of scrutiny – on the basis of the aims
identified in AP, Garçon and Nicot and of the analysis above in relation to the
applicant’s Article 8 claim."^
Or, to put it in other words, the court rejects the TWAW claim for someone without a GRC. (It does not say anything about TWAW after a GRC is granted as that was not the issue to be decided.)