Is the page uploaded?
No. The page is read in this tab and translated by the translator built into your browser; this site keeps no copy because it never receives one. The only request translating causes is the browser fetching a language pack from its own vendor the first time you use a pair, and that request carries nothing of the page.
Does it read right to left?
Yes, by default, because that is how manga is read: the bubbles are numbered from the top right, panel by panel. Choose left to right for a comic or a webtoon; the choice is remembered, and changing it after a read renumbers the bubbles without losing a translation.
Can it put the translation into the bubbles?
Not yet. Re-lettering the page is the button under the result, and it is in preview: pressing it counts a vote for building it and charges nothing. Today you get the numbered script, which you can copy or download as text or Markdown.
Which languages can it read on the page?
Japanese, Chinese, the Latin-alphabet languages, and Russian, Ukrainian or Belarusian with a second recogniser chosen in From. Korean lettering is not read yet. Whatever was read can be translated into any of the thirty-nine languages your browser's translator lists, where the browser offers that pair.
Can I translate a whole chapter?
One page at a time today. A chapter from a ZIP or CBZ is the second button under the result, in preview; pressing it counts a vote for building it and charges nothing.
Why does it not translate in Safari or on my phone?
The translating is done by the translator built into Chrome 138 or Edge 148 and newer, on a laptop or desktop, and other browsers do not offer one to a page yet. There the tool still reads the bubbles in order, so the script can be copied into any translator you trust.