The maximum default number of lookup columns per list based on MS best practice is 8, otherwise; it would show this error if you try to use more.
This is not related directly to SPARK Forms as this limitation is configured by MS to maintain best performance on SP farm and prevent resources consuming.
You can change the maximum lookup columns value in your central administration page on your own responsibility and you should be aware of such decision.
You can change it like this:
Central Administration > Application Management > Manage Web Application > Your Web Application > General Settings > Resource Throttling.