Closest you'll get to a style guide might be the iOS Human Interface Guidelines / https://developer.apple.com/design/human-interface-guidelines/ios/overview/themes/ Typography
Your example, tho, might be something you'd want to bounce off of support...use the 'Contact Us' link, below.
Thank you for your reply! I'll point our L10n team to the iOS Human Interface Guidelines and also try to reach support.
Apple has limited amounts of Japanese documentation and references the English documentation for further details. Below are some examples:
Japanese hints page for User interface that mentions the Human Interface Guidelines
Overall Japaense documentation
However, i couldn't find any specific styleguide by Apple regarding the spacing around English text.
I did run into a styleguide provided by the Japan Translation Federation with a definitive suggestion:
Do not put single-byte spaces between single-byte text and double-byte text.
The Japanese version http://www.jtf.jp/jp/style_guide/pdf/jtf_style_guide.pdf notes the same. I can't provide the example here because this forum does not accept Japanese characters.
Hopefully the L10n team will honor this instead of Microsoft's...
>Hopefully the L10n team will honor this instead of Microsoft's...
Speaking as someone who has written entire corporate style guides for major tech corporations in Japan, South Korea and China, when teams get into such platform-centric debates, I try to push for compliance that favors consistency, regardless of platform, not only in how the UI's contents look to the user, but what allows the various factions involved to do their individual work while being able to find comfort in a process that helps them as a whole, rather than one that forces them to defend, comply or make concessions, etc.
People tend to work better when they agree and find common ground on what's best for them -and- their users. Good teams will usually make the right choice when presented with reasonable options.
Instead of using contact us, i filed a radar regarding Apple's Japanese documentation inconsistency when it comes to using or not using half width spaces around English text