Hi Jan,
You can go to JSPM or SDM and check the patch level and compare to Stack in SMP.
Additionally
On the initial screen of systeminfo, there you will find version of sap.com/SAP-JEECOR and sap.com/SAP-JEE. This will give you SP level of your netweaver As Java system.
Hope this helps.
Regards,
Deepak Kori