Then practice in private or on a different series. It's seen as a major asshole move to come in and snipe a manga which already has somebody actively translating it,
especially when the quality is worse. There are plenty of series out there with nobody translating them yet.
Edit: if you want a bit of constructive criticism on this chapter though:
- Typesetting could use some work. The line spacing is very inconsistent, and for example on page 8, the bubble starting with "in the meantime..." - 'meantime' could easily have fit on the second line, rather than breaking the word.
- Your font choice isn't the worst I've seen, but deffo not the best. I'm not a TL/TS so I'm not sure what font(s) are commonly used, but I'm sure there are some decent free comic-esque fonts out there.
- You need to work on writing sentences from the correct point of view when the pronouns are omitted in the original Japanese. For example, again on page 8: "I want to hide with a blanket [...]" was obviously meant to be "she wants to hide [...]", and probably would've been caught with some more careful proofreading.
Overall, far from the worst I've seen for a first attempt. I've seen worse from long-established groups tbh, but again, sniping is a dick move. Either pick a different manga that doesn't have an active TL, or contact the current TL and see if you can work together if you really want to work on this specific series.