Higurashi Mei's raw files can be downloaded from one of these sites:

OG upload by The Omega Bodega.[mega.nz]

There's also another upload with different content on the Internet Archive.

https://archive.org/details/higurashi-mei-game-files

These raw files include various updated .apk that can be played on your phone or via emulation, however they try to connect to unavailable servers. It's not impossible to provide fake servers to an online software (I've done this with an old MMORPG called Yogurting), but there's no tool yet to do that with Mei.

It also includes the extraction tools that were used to develop the English translations.

As for the English translations; those are a collection of great Ren'Py ports made by @TsukuyamiTLs, not all of Mei's story arcs are translated yet and the proyect seems pretty much dead by now, but there's still a fair amount of content already available in English.

If you're well versed in Japanese, you can try reading Higurashi Mei from this YouTube playlist that recorded most (if not all) of its story arcs.

• youtube.com/playlist?list=PLyXXS8qfD_qiRLsX8TZFXmS-RK91WWekk&si=jlPkCQ4zt4Y1k8v8

It's been uploaded by リン酸ちゃんねる (@rinsan_ch) and contains all of the main story arcs.

It's a pretty faithful way to enjoy it, I should probably download it and keep it on a .rar file just in case it takes down for any reason. If I do so, I'll update this guide to a link with it.

• The Witch's Bloody Birthday Banquet (Event).
  
• Nao SSR story.
  
• Beatrice SSR story.
  
• Erika SSR story.
  
• Dlanor SSR story.

Note from translators: The Witch's Bloody Birthday Banquet should be read before any of the SSR stories. The SSR stories may be read in any order.

Link: http://github.com/Tsukuyami-TLs/higumei-engine-public/releases/tag/v0.0.1

• 1983, The Bewilderment of Ange Ushiromiya (Event).
  
• Rika SSR story.
  
• Akasaka SSR story.
  
• Battler SSR story.
  
• Ange SSR story.

Note from translators: 1983, The Bewilderment of Ange Ushiromiya should ideally be read before any of the SSR stories. The SSR stories may be read in any order.

Link: http://github.com/Tsukuyami-TLs/higumei-engine-public/releases/tag/v0.1.1

• "High School Student" Rika and Satoko SSR Story.
  
• "Theatergoer of the Torus" Eua SSR Story.
  
• "The Fifth Year of Innocence" Event Story.
  
• "Lucia Christmas Eve" Rika and Satoko SSR Story.

Note from translators: Ideally, the stories should be read from top to bottom as listed above (release schedule). Most importantly, read the Christmas event story before the Christmas SSR stories.

Link: http://github.com/Tsukuyami-TLs/higumei-engine-public/releases/tag/v0.2.1

• "Super Dimension Academy Z" (Event).
  
• "Borg Decker" Keiichi.
  
• "Galactic Patrol" Rika.
  
• "Dark Hero" Keiichi.

Note from translators: Read the Event Story before "Borg Decker" Keiichi and "Galactic Patrol" Rika. The "Dark Hero" Keiichi SSR can be read independently.

Link: http://github.com/Tsukuyami-TLs/higumei-engine-public/releases/tag/v0.3.0

As for now, Tsukuyami has been inactive on Twitter and Discord, and their fifth translation seems to be frozen for a long time now.

This iteration of Higurashi Mei has its own page on 'the visual novel database' (vndb.org/r103002).