Not a lawyer either, but I expect that if you kept contagious/non-distributable hyphenation files out of your app, included the ones you could, and then allowed users to import other dictionaries they'd found on the network or written themselves then you'd be reasonably safe. It would raise the hurdle for users, but your code would not then be including the copyrighted files, after all.
Can I point out, though, that 'I can't afford to make my work open source', is quite easily countered by the counter-argument 'don't think you can profit from the hard work of others for free, then'. I expect that what you *should* be asking is not how you can avoid GPL, but how you can get in contact with the respective authors to say to them "I hope to make X from each sale of this closed-source app, and it would be neat if it could include your work, can we reach some kind of deal for a separate commercial licence?" David
