RPG Insanity

There is a Treasure (No. 20 Black Bug of Horror) given IIRC by Maidame Curie that's wrongly translated. The current translation suggests that it's a really crappy Treasure: "Inflicts 1 Flinching on an enemy that has inflicted at least 80 damage in 1 turn". The correct word should be "was" - that was inflicted.
As it turns out seeing all events in the game is not enough to get the book to 100%. Players must also see all modes in these events to raise the value to 100%.

Thanks for letting us know. I've already made it my habit to try out each unknown event choice first, even if it means to miss out on benefits once or twice.

It seems some of the recent Exe Create Games weren't translated by John Sears or Nathan Duckworth, so we might have to be lenient with some "first-timers". Each of them followed some translation patterns that I wasn't fully satisfied with (even though I'm not a native English speaker and only know a few Japanese words), but in general and overall, I think they all did an at least decent job.

Denver Mirror translation is worded wrong. This card give "all" effect to your attack card for that turn.

Yeah, I used "Denver Mirror" during theme deck 4 dungeon runs before discovering "Gravity Burn". The card effect's translation would have been all right if it had just said "attack card" instead of "enemy card". On the other hand, I was pretty sure what the effect description really meant, and the card indeed works as intended by making all your single-target attack cards during this turn attack all enemy targets. Still no match for "Gravity Burn".

Full slash somewhat only count as "all card" and doesnt get bonus from "slash" related effect.

I never felt the urge to add a "Full Slash" to my deck, so I didn't notice.

There's an interesting little (harmless) bug involving the "upgrader". If you have no cards that can be upgraded while encountering the "upgrader", the upgrade list is empty and you can simply leave by pressing "Esc". Last time under these circumstances, out of curiosity during a theme deck 4 run, I pressed "Enter" instead. Lo and behold, the game told me I just had upgraded my "Light Slash" (the very first card of theme deck 1). At least the ghost "Light Slash" didn't appear in my deck afterwards.