First of all, I would like to say that I do not think that the proving of conjecture had direct influence to the fact that it started to be written in a different manner. :-) Something like: for uncertain things we use гипотеза х, but for known things x-гипотеза.
Regarding to the question of what sounds better to Russian ear, the answer is as usual: it depends.
Traditionally Russian has two types of constructions:
1. теорема/гипотеза/теория/уравнение + <сущ. в родительном падеже> (Noun + noun in Genetive)
F.e. уравнения Максвелла, теория чисел, теория струн
2. <прилагательное> + теорема/гипотеза/теория/уравнение (adjective + noun)
F.e. Евклидова геометрия, флуктуационная гипотеза.
In Russian the first way is the most commonly used for names of theories.
In English the first way corresponds to theory of + noun and is quite rarely used. Example: theory of relativity. But the most common construction in English is attributive noun + noun. All my examples of Russian way 1. will be translated using attributive noun in English: Maxwell equation, number theory, string theory.
The third way in Russian like Континуум-гипотеза, abc-гипотеза is calque from English. It became more fashionable now in the days of globalization when researches read a lot of material in English and translate their works into English, so why bother doing full adoption into language - it may be more practical to keep it closer to English, less re-wording when translate. So while гипотеза континуума sounds more Russian Континуум-гипотеза sounds cooler and is shorter. Compare with older adoption: теорема вириала, was not taken as вириал-теорема.
Abc-гипотеза is even more obvious candidate to the use of English way with attributive noun in front because it is anyway written in Latin alphabet and "abc" does not decline. So it does not sounds Russian even if you put "abc" after the "гипотеза".