Pretty sure the dev once said that translating Barrage wasn't worth the effort, hence why they didn't translate the rest of their games.
Dev isn't totally wrong, in general at least. There has been honesty very few cases where an official translation has brought in a lot more sales. Especially compared to the original. Anyone who does so it's more in appreciation to their overseas fans whether than for actual profit.
Using hatahata games as an example:
Unholy Disaster: 8.8k sales JP, 1k sales EN. That's a positive reaction though sadly not common place.
Unholy Torture (even taking into account it came out during holiday season): 3.5k sales JP, 290 EN.
Barrage actually did really good: 3.6k JP, 1.9k EN. And this is more likely to gameplay appealing more to western audience then having a ENG translation.
Pirating because of Language barrier does have some reasoning but it's mostly just used as an excuse. A lot more westerns just don't want to pay for porn, it's simple as that.
If you want a clear distinction of JP vs West buying habits, a quick look at the all time rankings will give you the best picture.
The top 3 most download games in Eng DLsite (one not even having a Eng translation) combined doesn't even reach a third of the number 1 game on JP. (Seriously, no one will ever remove Sylvie from her throne.)