A.D.

Sometimes we want the front end of our blog to be translated for the users, but keep the backend admin panel in English. Admin in English with Switch does just that. It lets you switch your backend administration panel to English from admin toolbar, even if the rest of your blog is translated into another language. This plugin allows turning English language on and off for each user’s back-end independently.
For more information about original Admin in English plugin please visit https://wordpress.org/extend/plugins/admin-in-english/ page.

Admin in English with Switch

This plugin is an extended version of Admin in English plugin (v1.2) developed by Nikolay Bachiyski. See the Description for more details.

ThemeCatcher

With this add-on, a form can be translated into multiple languages using WPML. Gone are the days of having duplicate forms for each language!
<h3>Features</h3>
Translate unlimited forms into other languages through WPML.
Deep integration
All user-facing strings are fully translatable, including all form settings, fields settings and validation error messages. Emails sent to users can also be translated, along with the confirmation (success) message shown after the form is submitted.
Advanced WPML compatibility
Compatible with both the String Translation workflow, and the Advanced Translation Editor.
Datepicker/timepicker support
Automatically converts the locale of the datepickers and timepickers into the current WPML language. The dates and times will be automatically formatted according to regional standards.
<blockquote>
Note: this plugin is a free add-on for the <a href="https://www.quform.com/" rel="nofollow ugc">Quform Premium WordPress Form Builder plugin</a>. For this plugin to function, Quform version 2.16.0 or later, WPML version 3.2 or later, and the WPML String Translation plugin must be installed.
</blockquote>

Quform WPML

Translate Quform forms into multiple languages using WPML.

Admin in English with Switch vs Quform WPML