You can create Revenue Arrangements from a Journal Entry, provided that you add an Income account, add a Revenue Recognition Rule, Rev Rec Start Dates/End Dates (Optional) and name. Please check SuiteAnswers Id: 49249
For example:
1.) Navigate to Transactions > Financial > Make Journal Entry
2.) Adde a Sales Order Line with Income Account and Revenue Recognition Rule:
3.) Updated Revenue Arrangement and Plans
Results:
This created a Revenue Arrangement with the Journal Entry as its source.

