Yes, yes I played most games before and I know that SP still had a lot commus. I was taking 1 and 2 for example. Also if you are talking about story driven commus, platinum stars and Stella stage clearly had less than the other games. And you asked about stella stage, so I talked about Stella stage.
If you read my comment I only stated that Stella stage doesn't have many commus besides the morning and promotion commus which CAN REPEAT. The story commus you get from starting to produce an idol, then one for each rank up ( which these games obly have 1 of each. You don't get B1 B2 B3 and so on) and the ending.
I liked the commus because I like the interactions between the girls and producer or each other. To come back to that question. And yes, while I can't read all kanji, I can understand Japanese spoken pretty well, after all I've been learning japanese
But the game won't be much fun for you if you don't like the repetitive rhythm game aspect.
Because some rank ups let you play more than one song, dame goes for all-star lives.
The last thing. There are full versions of the songs out. Not as master artist but as platinum master and Stella master albums which give you the new songs in full version. There are also live venue CD which give you the solo versions of the idols which participated in each songs master version
(Like haruka, Makoto, Ami,Mami and Iori getting solos of miracle night and so on)