Quick answer: Use pseudolocalization to catch overflow and missing strings before real translations arrive, test each language for font and encoding support, and capture the active language and a screenshot on every report. Localization bugs are visual and language-specific, so the language context plus an image is what makes them fixable.
Adding languages to your game can dramatically expand your audience, and it can also break your carefully built interface in a dozen ways that English never revealed. German words overflow your buttons, missing translations fall back to placeholder keys, an unsupported character renders as a box, and a right-to-left language mirrors your layout in ways you never tested. Localization bugs are their own category, mostly visual and always language-specific, and catching them takes a deliberate QA process plus capturing the language context behind every report.
Localization breaks things English hid
Your UI was almost certainly designed and tested in one language, and it fits that language perfectly. Other languages do not respect those dimensions. German and Finnish words are notoriously long and overflow buttons and labels. Japanese and Chinese need different fonts and line-breaking. Right-to-left languages like Arabic and Hebrew require mirrored layouts. None of these problems exist until you localize, and then they all appear at once.
This means localization QA is not just checking that the translations are accurate, it is checking that your game holds together visually and technically in every language. A perfect translation that overflows its text box is still a bug, and the most common localization defects are layout and rendering problems, not mistranslations.
Use pseudolocalization early
The most powerful localization QA technique is pseudolocalization: replacing your text with a transformed version that is longer, uses accented and wide characters, and is wrapped in markers. You can do this before any real translation exists, and it instantly reveals overflow, clipping, and missing-string problems across your entire interface.
Pseudolocalization catches the structural problems cheaply and early, while you still have time to fix your layouts. Strings that are not externalized show up because they do not get transformed, overflow shows up because the pseudo text is longer, and encoding problems show up because of the wide characters. Running pseudolocalization should be a standard part of your build long before you commit to real translations.
Test fonts and encoding per language
Each language you support needs a font that contains its characters, and a missing glyph renders as a box or a blank. Test every language with its real script, not just the Latin alphabet, and verify your font fallback chain handles characters your primary font lacks. CJK languages and scripts like Thai or Devanagari are common sources of missing-glyph bugs.
Encoding issues lurk underneath. If any part of your pipeline assumes a single-byte encoding, multi-byte characters get mangled, producing garbled text. Test that strings round-trip correctly from your translation files through your game to the screen, and capture the active language in reports so a garbled-text report immediately points at which language pipeline is broken.
Capture language and a screenshot
Because localization bugs are visual and language-specific, the two most valuable things to capture are the active language and a screenshot. A report that says the text is broken is nearly useless, but a screenshot showing French text spilling out of a button, tagged with the language, is instantly actionable and tells you exactly which string and which layout need attention.
The active language field also lets you tell whether a bug is universal or specific to one translation. A layout that breaks only in German is a length problem, one that breaks only in Arabic is a mirroring problem, and one that breaks in every language is a structural issue. The language tag turns a pile of broken text reports into a sorted list by cause.
Setting it up with Bugnet
Add an in-game report option that captures a screenshot and the active language automatically, plus the current screen or menu. Bugnet stores them so your localization reports arrive with the image and language context that make them fixable, whether they come from your testers or from players using a language you do not speak.
Group reports by language and screen to see patterns: a cluster on one language and one menu localizes the problem precisely. Because players in a language you cannot read can still file a report with a screenshot, you get visibility into localization bugs you would otherwise never even know existed, which is invaluable when you are shipping in languages outside your team fluency.
Recruit native-speaker testers
Automated techniques catch structural problems, but only a native speaker catches the subtle ones: a translation that is technically correct but reads awkwardly, a term that is wrong in context, a cultural reference that does not land. For the languages that matter most to your audience, recruit native-speaker testers and give them the same easy report path your other testers use.
Make it easy for them to flag both bugs and quality issues, with a screenshot and the language captured automatically so you can act even when you cannot read the text yourself. Native-speaker feedback combined with pseudolocalization and per-language technical testing gives you full coverage, from the structural bugs that break your layout to the nuance that makes a translation feel native rather than machine-made, which is what players in each language actually judge you on.
A perfect translation that overflows the button is still a bug. Test the layout, not just the words.