"I didn't like attending her soccer games."
Translation:Je n'aimais pas assister à ses matchs de foot.
Without additional context, both the passé composé and the imperfect work here. While it's true that the imperfect often translates into English as "used to do X" or "was X-ing", it would be an inaccurate oversimplification to say that it always translate in one of these ways. The nature and context of the action determines which tense should be used.
The passé composé is used for past actions that are completed, past actions that happened at one or more specific points in time, and past actions that represent a new state of being or feeling. The imperfect is used for past actions that are incomplete or not known to be complete, past actions that are regular or indefinite in number, and past actions that represent an ongoing state of being of feeling. You can see here for more details.
In this sentence, it could go either way depending on context. For example, if I still don't like attending her games, then the imperfect is appropriate since my dislike is ongoing. On the other hand, if for example I didn't like attending her games last year but I don't mind attending them this year, then my dislike represents a completed action in the past, and the passé composé is appropriate.
Whilst all that you say is true, I would say that, as a result of that advice, in the singular "Je n'ai pas aimé assister à son match de foot." is, as a single finite event, more likely than the imparfait, but that in the plural "Je n'aimais pas assister à ses matchs de foot." is, as an extended series of events, much more likely than passé composé.