The Nextdent 5100 can only print Nextdent resin well. The bar coding is only a small hurdle. The real problem is that there is no way to adjust exposure time or printer movement speeds to create the proper print parameters for any other resins. Even if a print were to be successful it would not reach the proper physical properties and may not be dimensionally accurate. Any scale factor adjustments built into the profile are for Nextdent model resin.
If you are finding the models "soft", this is an indication of a potential problem with your post processing technique. IPA of at least 90% is recommended and 99% will work best. Do not let parts stay submerged more than 5 minutes total. Make sure to rinse off the parts with water and dry thoroughly before putting them in the light cure box. Models should be cured in the UV light for 30 minutes.
The other thing to be aware of is that the model material needs to be rolled on the mixer for 2.5 hours prior to the 1st time you open the bottle. After that it should be mixed at least 5 minutes prior to adding new material to the resin tray. Make sure resin is well mixed in the tray prior to starting a print.
When done properly, the models should be very hard.