How to Fix Placeholder Mismatches

A Param badge (red) appears when a placeholder in the base locale doesn't match what's in the target translation. This is a hard error: at runtime, a missing placeholder means the variable value is silently dropped from the displayed string.

What counts as a placeholder#

StringLane treats these as placeholders, depending on your file format:

Finding out which placeholder is wrong#

Two places tell you:

• Hover the red Param badge. The tooltip names the placeholder that is missing from the target, or the extra one that appears in the target but not the base.
• Read the Issues Panel (⌘J). Each mismatch is its own row, naming the key, the locale and the specific placeholder, with no hovering, and you can work down the list.

The one-click fix#

When StringLane can reconstruct the correct string on its own, a 🔧 wrench button appears next to the Param badge. Click it and the placeholder is restored in place.

This is a deterministic repair, not an AI call: it is instant, free, and produces the same result every time. Reach for it first: the manual and AI routes below are for the cases where the wrench does not appear.

Fixing the mismatch manually#

1. Click the cell to edit it.
2. Add the missing placeholder in the correct position within the translated string.
3. For ARB, placeholders are case-sensitive and must match exactly: {userName} ≠ {username}.
4. Press Enter to confirm. The Param badge clears immediately if the fix is correct.

Example:

• Base (English): Hello, {name}! You have {count} messages.
• Broken Spanish: ¡Hola! Tienes mensajes.
• Fixed Spanish: ¡Hola, {name}! Tienes {count} mensajes.

Fixing with AI re-translation#

Click ✨ on the Param cell to re-translate it. The AI is given a hard instruction to preserve all placeholders in the correct format. In most cases, this produces a clean result without the mismatch.

If re-translation still produces a mismatch (rare, usually on complex ICU strings), edit the cell manually.

Param autofix#

For simple cases where the only issue is a missing placeholder at the end of a string, StringLane may offer an Autofix option directly on the badge. Click the badge → click Autofix → the placeholder is appended to the translation automatically.

Autofix is a heuristic: review the result to ensure the placeholder is in the grammatically correct position for the target language.

Preventing param mismatches#

• Use AI translation with product context: the AI is explicitly instructed to preserve placeholders.
• Add @description to ARB keys with variables: the description is passed to the AI, giving more context for correct placeholder placement.
• Review translated strings with variables after bulk translation: filter by Issues (⌘⇧I) to find Param badges quickly.