please according this method to modify your project file.
For example: Install Japan Language MUI in WES7 SP1, You must to setting a default language in ICE.
1. Insert Japan Language Pack
2. Setting International-Core_x86
l InputLocal = ja-JP
l System Locale = ja-JP
l UILanguage = ja-JP
l UserLocale= ja-JP
3. Setting International-Core-WINPE_x86
l InputLocal = ja-JP
l SetupUILanguage->UILanguage= ja-JP
l SystemLocal=ja-JP
l UILanguage => ja-JP
l UserLocale=> ja-JP
