fix: Use Interface Language instead

src/shared/components/post/post-form.tsx

@@ -4,7 +4,7 @@ import {
   myAuth,
   myAuthRequired,
 } from "@utils/app";
-import getUserPrimaryLanguage from "@utils/app/user-primary-language";
+import getUserInterfaceLangId from "@utils/app/user-interface-language";
 import {
   capitalizeFirstLetter,
   debounce,
@@ -324,12 +324,13 @@ export class PostForm extends Component<PostFormProps, PostFormState> {
   }
 
   render() {
-    const userPrimaryLanguage = getUserPrimaryLanguage(
-      UserService?.Instance?.myUserInfo
-    );
-
     const url = this.state.form.url;
 
+    const userInterfaceLangId = getUserInterfaceLangId({
+      myUserInfo: UserService.Instance.myUserInfo,
+      allLanguages: this.props.allLanguages,
+    });
+
     return (
       <form className="post-form" onSubmit={linkEvent(this, handlePostSubmit)}>
         <NavigationPrompt
@@ -496,7 +497,7 @@ export class PostForm extends Component<PostFormProps, PostFormState> {
         </div>
         <LanguageSelect
           allLanguages={this.props.allLanguages}
-          selectedLanguageIds={[userPrimaryLanguage]}
+          selectedLanguageIds={[userInterfaceLangId]}
           siteLanguages={this.props.siteLanguages}
           multiple={false}
           onChange={this.handleLanguageChange}