It should open without any problems. However any new version 14 techniques used will not appear when opened in 13.
WF7A, Would like to know, Which bug are you referring to ? Thanks
There's a screen draw problem in v14.x (Mac, but I don't know about PCs) with themes that use slices, e.g., the Electric theme--mysterious lines appear at different zoom levels.
I reported this bug about a week or two ago and it's been confirmed.
For More Information see: Mysterious lines appear different zoom levels (FMPA v14 Mac)
This is one of many acknowledged bugs that can be found in the Known Bug List thread here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: https://www.dropbox.com/s/jt09b82i0xijbu3/FMP%20Bugs.zip
But a far more serious bug is a case where unintended changes take place in the order of the script steps in the new scripts workspace.
For More Information see: FMPA14 Script step line jumping