I've found a workaround in the meantime.
53 and 54 have the certificate transparency problem, and 55 on arch Linux ARM has this memory alignment problem.
To get a working chromium (for all sites), install any version pre-55.x of chromium, old packages can be retrieved from
http://tardis.tiny-vps.com/aarm/packages/c/chromium/ . I grabbed chromium-54.0.2840.90-1-armv7h.pkg.tar.xz
Then upgrade to that version:
$this->bbcode_second_pass_code('', 'sudo pacman -U chromium-54.0.2840.90-1-armv7h.pkg.tar.xz')
Then start chromium with the following arguments from command line:
$this->bbcode_second_pass_code('', 'chromium --variations-server-url=https://clients4.google.com/chrome-variations/seed --fake-variations-channel=stable')
which was provided from this thread:
https://news.ycombinator.com/item?id=12953172This enables "Finch", a method of getting flags from google at application startup to dynamically config the browser. This is enabled in google chrome by default and disabled in chromium by default.
You can edit your GUI application launcher for chromium to include these arguments on every launch until a fix is available for 55.
Note that this has some privacy concerns that are mentioned in the thread, i.e. notifying google every time you launch the browser and allowing them to dynamically configure your browser on start, but this is no worse than running google chrome.