I'm honestly shocked that the earlier games didn't have higher sales! I always thought the first five Langrisser games had Fire Emblem-like sales in Japan and that it was one of the biggest (old) SRPG franchise. It all went down after L5 of course (and I knew L5 itself didn't do that well sales-wise), but I thought the previous games had been very successful.
After a quick look I'm not finding much sales data, but one site states 170k copies total for the entire franchise..? That sounds dreadfully low to me.
Anyway, first week sales for the Langrisser remake is over twice the 3ds sales (20k vs 8k), so there's that at least! Keeping Japanese voice-acting is sort-of common for lower budget games nowadays (for example, the Atelier series is keeping the Japanese voices only lately), so I don't think that would be a big issue regarding localization. I do prefer English dubs when possible, but I'm certainly willing to sacrifice it if it means getting a localized version of the game!
Blurred event pictures? Which version do you have? I only played the Switch demo so far, but the cutscene event picture looked fine to me? But yeah, the general sprites aren't great. Battle animations off is a must in my opinion, but on the map I've played worse-looking than this. It's certainly on the lower end of sprites, but not that bad imo.