Cavesa wrote:"I was speaking French today" is still passé composé. Imparfait has different uses. It might just be appropriate to specify the time a bit more, or to give more context to the sentence, to make it more practical.
"I was speaking French today" isn't the passé composé, it's the imparfait.
The difference: the imparfait tense is used to describe events that happened in the past that happened over a period of time, (i.e. as a continuous action) whereas the passé composé is used to describe events that happened at a specific time. The imparfait can also be used to describe past habitual actions, such as 'I used to...', etc, as well as events that were going on when an event happened (e.g. 'I was watching tv when someone knocked on the door').
The 'I was' in 'I was speaking French today' means the action took place over a period of time, as opposed to at a specific time, meaning it was a continous action, so it's the imparfait, not the passé composé. I suggest you watch this video, which was created by a French native and expert teacher, to understand the difference between the two:
https://www.youtube.com/watch?v=JK5OMjjAc8A
My original question wasn't about the difference between the passé composé vs the imparfait, though. It was about whether the perfect progressive tenses exist in French or not. Thanks for the replies regarding that question.