Going through the game a bit I've started identifying areas that will need manual translation. Most of these are just one or two words, and some of these could probably be blanked out all-together but others will be more work.
01. The Mode Select Screen

This is arguably the most important translation as it lets the player know which game mode they're selecting.
02. The Instruction Screen:

I wonder if this is actual text or a static image.
03. The Attention Screen:

This Screen seem to be instructing the player that they can type a single Japanese word multiple ways. Since this is completely irrelevant to the English version I wonder if this screen could simply be bypassed. Again, not clear if this is text or an image.
04. The Chapter Selection Screen

chapter name and description could probably be taken from the English version
05. "Press the Enter key to skip" text

This appears on several of the other screen as well, I wonder if the text is only stored in 1 place and then referenced multiple times.
06. Subtitles

The Cutscenes in both attract mode and while playing have sub-titles along the right side of the screen. The English version doesn't have any at all so I'd think these could simply be blanked out, or removed.
07. Boss Instructions

before each boss battle there are instructions on how to defeat, The text could probably be taken from the English version. After Mode Selection this is arguably the most important translation as it's relevant to game play.
08. Score screen:

At the end of each level the score screen has some text on the right hand side.
Others that I couldn't find good screenshots of but I know exist are
09. Attract Mode Tutorial
This is several on-screen text bubbles that appear as part of attract mode where the game explains how to play.
10. Score Attack messages
When playing score attack mode there is a screen with some text that appears before the game starts, and another message that appears on screen during gameplay. There may be others, I haven't played this mode much.