Steps to reproduce:
1. Open the demo page http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx
2. Switch to the 'HTML' mode of the RTE and replace all existing HTML content with the following HTML snippet:
<div>text</div>

3. Switch to the 'Design' mode of the RTE and click once on the 'text' word;
4. Switch keyboard language to Japanese and select 'Hiragana' input type. Place focus on the 'text';
5. Type the 'a' and 'e' characters;

Expected result:
The 'あえ' characters are typed.

Actual result:
Just 'え' character is typed. The 'あ' character is replaced by the 'え'. 

Note:
The first character disappears.
You may need to try several times to reproduce the issue.
The issue is reproducible in Chrome (Version 54.0.2840.99 m).
The issue is not reproducible in Firefox and IE11.

Screencast reproduction: http://screencast.com/t/Lj6plU0di99



Workaround:

<telerik:RadEditor ID="RadEditor1" runat="server">
<Content><p>test</p></Content>
</telerik:RadEditor>

<script>
var editorPrototype = Telerik.Web.UI.RadEditor.prototype;
var onKeyDown = editorPrototype._onKeyDown;
editorPrototype._onKeyDown = function (e) {
if (e.composed) {
   this._pendingTextTypeCmd = {};
}
onKeyDown.call(this, e);
if (e.composed) {
   delete this._pendingTextTypeCmd;
}
};
</script>