Just a personal anecdote. I have been reading a lot of Italian lately (with the help of Google Translate). I already read Spanish fairly well. I have studied French, Portuguese and Italian, and I can read Portuguese and French to some extent, Portuguese better than French.
But I confess that I am quite lost with Italian. This is worse than French and worse than Portuguese. A couple weeks of wading through this stuff hasn’t made me understand it any better.
Portuguese and Galician are said to be so close that they are a single language. I don’t agree with that at all, but they are very close, much closer to Spanish and Portuguese. Intelligibility may be on the order of 80-90%.
Nevertheless, the other day I tried to read a journal article on Galician. It looked like it was written in Portuguese, and who would write in Galician anyway? I copied the whole thing into Google Translate and let it ride. I waded through the whole article, and I must say it was a disaster. I had a very hard time understanding many of the main points of the article.
Then I remembered that Translate works on Galician now, so I decided on an off chance that the guy may have written the piece in Galician for some nutty reason. I ran it through Translate using Galician as target. The article went through perfectly. You could understand the whole thing. It was then that I realized how far apart Portuguese and Galician really are.
You can try some other experiments.
Occitan is said to be nearly intelligible with Spanish or maybe even French, better if you know both. There’s no Google Translate for Occitan yet, but I had to deal with a lot of Occitan texts recently. I couldn’t make heads or tails of them despite by Romance reading background. So I tried using Translate to turn them into Spanish or French. French was a total wreck, and there was no point even bothering with that. Spanish was much better, but even that was a serious mess.
Now we come to the crux. Catalan and Occitan are said to be so close that they are nearly one language. Translate now works in Catalan. So I ran the Occitan texts through Translate using Catalan. The result was a serious mess, but you could at least understand some of what the Occitan texts were about. But no way on Earth were those the same languages.
People keep saying that if you can read Spanish, you can read Portuguese. It’s not true, but you can see why people say it. Try this. Take a Spanish text and run it through Translate using the Portuguese filter. Now take a Portuguese text and run it through Translate using the Spanish filter. See what a mess you end up with!
Despite the fact that I can read Spanish pretty well, I have tried to read texts in Aragonese, Asturian, Extremaduran, Leonese and Mirandese. These are so close that some even say that they are dialects of Spanish. But even if you read Spanish, you can’t really read any of those languages, and they are all separate languages, I assure you. Sure, you get some of it, but not enough, and it’s a very frustrating experience.
There are texts on the Net in something called Churro or Xurro. It’s a Valencian-Aragonese transitional dialect spoken around Teruel in Aragon in Spain. It also has a lot of Old Castillian and a ton of regular Castillian in it. Wikipedia will tell you it’s a Spanish dialect. Running it through both the Spanish and Catalan filters didn’t work and ended up with train wrecks. I doubt if Xurro is a dialect of either Catalan or Spanish. It’s probably a separate language.
There is another odd lect spoken in the same region called Chappurriau. It is spoken in Aguaviva in Teruel in the Franca Strip. The Catalans say these people speak Catalan, but the speakers say that their language is not Catalan. Intelligibility with Catalan is said to be good. So effectively this is a Catalan dialect.
I found some Chappurriau texts on the Net and ran them through Translate using Catalan as the output. The result was an unreadable disaster, and I couldn’t really figure out what they were saying. Then I tried the Spanish filter, and that was even worse. I am starting to think that maybe Chappurriau is a separate language as its speakers say and not a Catalan dialect after all.
I conclude that the ability to cross read across the Romance languages is much exaggerated.
Not only that, but many Romance microlanguages, transitional dialects and lects that are supposedly dialects of larger languages may actually be separate languages.