Hi Gunderic,
On checking the PAM of Xcelsius 2008 Service Pack 5, we see that Win 10 is not supported. That means you may or may not face issues once you get your OS upgraded, but SAP would not be helping you out here.
Below is the link to the PAM of Xcelsius 2008 SP5 :
http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/f0878e4d-420d-2f10-3fb9-
d8cffc57b397?QuickLink=index&…
You might want to consider upgrading both Xcelsius & Windows OS to a version where both are compatible & supported.
Do let us know in case of any queries.
Regards,
Monish