I'm also seeing Xcillion as Bootstrap 3 (after upgrading to 9.6.0). Besides that, in Extensions I see that Xcillion has a 10.0.0 upgrade available. If I click that link I get an error:
Upgrade Details Unknown
The extension you have selected has an upgrade available, however, the vendor has not informed the upgrade service of the suggested location to acquire the upgrade for the component. Please contact the vendor for assistance.
DNN Platform Update Service Version 1.0.11
I know there are plans to upgrade Xcillion to BS 4 but I've not been able to know when will it be included in DNN Platform, os if it'll be released as a separate extension.