When compiling reports with an old version of the libraries, namely 4.5.1, sometimes an exception will be thrown and the report can't be compiled.
The most typical case is complaining about "The type java.lang.CharSequence cannot be resolved. It is indirectly referenced from required .class files", and seem to happen when the report has some sort of short java code, for manipulating strings or localizing numbers.
Suggestions like the one found here (https://community.jaspersoft.com/questions/951391/type-javalangcharseque...) or here (https://stackoverflow.com/questions/24301986/the-type-java-lang-charsequ...), recommending setting the source level of the project to a lower one, don't work (tried from 11 to 1.8, 1.7 and lower).
In another case, an "out of bonds" of a frame element exeption was thrown, although the message was pretty absurd:
net.sf.jasperreports.engine.design.JRValidationException: Report design not valid :
1. Element reaches outside frame height: y=10, height=10, available height=10.
Checking in the editor, I can confirm that the height is 10 and it's complaining because the available height is 10 (it should fit, though). No way to solve it.