When RadEditor is configured with RenderMode="Auto", it renders fine on a mobile, but the Find and Replace throws a JavaScript error:
Uncaught Error: Sys.ArgumentNullException: Dialog Parameters for the FindAndReplace dialog do not exist
Parameter name: dialogName
at Function.Error$create [as create] (ScriptResource.axd?d=drtcXVcvAjvxxGTIp4ks_jsffAtTgDZa7F-xsErOE7x83oPLnSroIDP2Rlpln027LL6pHm8wDFlVd2TfNwyX9tsTD0IfApyfv4p2GRpAUsfag9bRTF3ZhqYQPg2KFASuXMmfKVcURGhOxnF7S60OLuj9cWAWD2oOw-AOIsKJVpoN8aJcHQVfLpfuW8e9J_z70&t=74693645:237)
at Function.Error$argumentNull [as argumentNull] (ScriptResource.axd?d=drtcXVcvAjvxxGTIp4ks_jsffAtTgDZa7F-xsErOE7x83oPLnSroIDP2Rlpln027LL6pHm8wDFlVd2TfNwyX9tsTD0IfApyfv4p2GRpAUsfag9bRTF3ZhqYQPg2KFASuXMmfKVcURGhOxnF7S60OLuj9cWAWD2oOw-AOIsKJVpoN8aJcHQVfLpfuW8e9J_z70&t=74693645:279)
at b.RadDialogOpener._getDialogDefinition (ScriptResource.axd?d=CcXTXAXm_2uXk6i-z8e-9-GUON7JgJld7fON2waeoUCDG-568SfljYE0OxAYq5S_l1j5QbPdt7yR5Ji7ARrlqe9xsoWPpTVgVVnsC2r0rN-hCMOIKe3sXa-glZDwstuHDCKnEGv03WuBZg3A1mEmGb3cZzVnLPok8zmI9TSFWuc1&t=6e6e42a6:199)
at b.RadDialogOpener.open (ScriptResource.axd?d=CcXTXAXm_2uXk6i-z8e-9-GUON7JgJld7fON2waeoUCDG-568SfljYE0OxAYq5S_l1j5QbPdt7yR5Ji7ARrlqe9xsoWPpTVgVVnsC2r0rN-hCMOIKe3sXa-glZDwstuHDCKnEGv03WuBZg3A1mEmGb3cZzVnLPok8zmI9TSFWuc1&t=6e6e42a6:65)
at c.RadEditor.showDialog (ScriptResource.axd?d=wYaAc3J2NgVJCu2P39J4xyGaoOdrMcpsgItEXwZ_xZ-mxwwqth9gFwZgQmz64y0L50bOGm0jxdnTOv_b92sCumvlnrhdNCqVSpfDTXuridpdeelSxC1ktLGb8SRXNUQSfAkHpn5XxFbvggex9gxJzw2&t=6e6e42a6:8753)
at Telerik.Web.UI.Editor.CommandList.FindAndReplace (ScriptResource.axd?d=wYaAc3J2NgVJCu2P39J4xyGaoOdrMcpsgItEXwZ_xZ-mxwwqth9gFwZgQmz64y0L50bOGm0jxdnTOv_b92sCumvlnrhdNCqVSpfDTXuridpdeelSxC1ktLGb8SRXNUQSfAkHpn5XxFbvggex9gxJzw2&t=6e6e42a6:5051)
at c.RadEditor.fire (ScriptResource.axd?d=wYaAc3J2NgVJCu2P39J4xyGaoOdrMcpsgItEXwZ_xZ-mxwwqth9gFwZgQmz64y0L50bOGm0jxdnTOv_b92sCumvlnrhdNCqVSpfDTXuridpdeelSxC1ktLGb8SRXNUQSfAkHpn5XxFbvggex9gxJzw2&t=6e6e42a6:9266)
at c.RadEditor._onToolClick (ScriptResource.axd?d=wYaAc3J2NgVJCu2P39J4xyGaoOdrMcpsgItEXwZ_xZ-mxwwqth9gFwZgQmz64y0L50bOGm0jxdnTOv_b92sCumvlnrhdNCqVSpfDTXuridpdeelSxC1ktLGb8SRXNUQSfAkHpn5XxFbvggex9gxJzw2&t=6e6e42a6:8619)
at Array.<anonymous> (ScriptResource.axd?d=drtcXVcvAjvxxGTIp4ks_jsffAtTgDZa7F-xsErOE7x83oPLnSroIDP2Rlpln027LL6pHm8wDFlVd2TfNwyX9tsTD0IfApyfv4p2GRpAUsfag9bRTF3ZhqYQPg2KFASuXMmfKVcURGhOxnF7S60OLuj9cWAWD2oOw-AOIsKJVpoN8aJcHQVfLpfuW8e9J_z70&t=74693645:47)
at ScriptResource.axd?d=drtcXVcvAjvxxGTIp4ks_jsffAtTgDZa7F-xsErOE7x83oPLnSroIDP2Rlpln027LL6pHm8wDFlVd2TfNwyX9tsTD0IfApyfv4p2GRpAUsfag9bRTF3ZhqYQPg2KFASuXMmfKVcURGhOxnF7S60OLuj9cWAWD2oOw-AOIsKJVpoN8aJcHQVfLpfuW8e9J_z70&t=74693645:3484
Render mode configuration in the web.config
<add key="Telerik.Web.UI.RenderMode" value="Auto" />
It seems, code is looking for FindAndReplace key in this._dialogDefinitions, but it's not there. However, the key FindAndReplaceSettings is there.