@danbjoseph I suppose that by definition a line should contain two or more points? @Jefferson_Francisco I invite you to take a look at the thread on Collect geotrace and geoshape improvements and see whether you would like to propose making this a geotrace requirement along with other proposed changes.
For now, you can add a constraint that requires two or more semicolons. The constraint will look like regex(., '^([^;]*;){2,}$'). This says the resulting geotrace (the dot in the regex function) must contain non-semicolon characters ([^;]*) followed by a semicolon (;), repeated 2 or more times {2,}.
Here is a form that shows this at work.