A learning platform must support many languages including ones with different scripts and text directions. What must be architectural rather than cosmetic?

What must be architectural

• Locale as a first-class dimension from the first row of data, since retrofitting it means touching every content table and every query.
• Text externalised from code, with a translation pipeline rather than a developer editing strings. A system where adding a language requires a code change has made language support an engineering constraint on a business decision.
• Layout that adapts to text length, since translations vary substantially in length and a design assuming one language's compactness breaks in others.
• Right-to-left support in the layout system rather than per component, because retrofitting it component by component never completes.
• Locale-aware formatting for dates, numbers, currency and sorting, applied through one mechanism rather than being reimplemented.
• Font loading for the required scripts, which for some scripts is a substantial payload and interacts directly with the performance budget.

What is genuinely cosmetic and can be deferred

Copy quality, idiomatic phrasing and cultural adaptation — important and not structural, and improved incrementally without a rewrite.

The content dimension specific to education

Content itself is per language, not merely the interface. That is a content-operations problem — production, review, versioning and synchronisation across languages — and it is far larger than the engineering problem, which is why the architecture must make adding a language cheap on the engineering side and the constraint purely a content one.

The quality variation that must be measured

Model and search quality varies enormously by language. A search index, a recommendation model or a moderation classifier tuned for one language performs differently in another, and a single evaluation set hides that — which means evaluation must be per language and the answer is frequently different per language.

The performance interaction

Additional scripts mean additional fonts, and fonts are a large payload on a constrained connection. Subsetting to the characters actually used, and loading with a sensible fallback so text is visible during load, is the difference between a usable page and a blank one — and it is a decision the internationalisation work makes on the performance budget's behalf.