I didn't conceive this sentence and I would certainly never use it. It's an example of the somewhat chaotic verb system in English.
Since you had provided a link I realized you did not conceive the sentence.
It is an interesting example but I don't think it is indicative of any chaos in the English verb system. As stated before, the English tenses are simple jigs, with a minor complication posed by a small number of irregular verbs. Those occur in most languages. Incidentally, the general rule is that the most frequently used ones are the ones with the most irregular forms so these get taken care of pretty soon into the learning process.
In English, all tenses can presented in a nice and simple to understand tabular format taking no more than one legal size (about A4) page. Another page, perhaps two with irregular verb forms and all combination are covered. In some cases it would take at least a page to convey all forms of just one Polish verb - even with the meager number of tenses in Polish.
I know from experience, i.e. being round lots of Poles learning English, that lots of them cannot grasp the different tenses, especially not in normal speech. If you're Polish and you can then congratulations :-)
One of the issues with learning a foreign language is the purpose. A lot of people's needs are pretty limited. An occasional tourist to an English speaking country will get away with one tense and about 1000 words. It's not going to be pretty but sufficiently good for basic communication. Now, try to have that same small arsenal of Polish words.
When I first came to the US I could easily talk about ambiguities in the English language as it comes through the pages of great literary works in the English language but I was afraid to take a written driving test in New Jersey's DMV. The likes of Chaucer, Hemingway or TS Elliot wrote on the subject very sparingly, so rarely did I come across terms such a "turnpike" or "double yellow lines".
Someone working in the US or UK will need a varying degree of competency. A journalist reporting on the Royal Family will certainly be expected to be highly proficient, while a bricklayer will will easily get away with rock bottom basics.
Not all of us are Shakespeares, neither do we aspire to be. Who would the audience be?
I was taught Latin when I was in high school and then in one of Polish universities - 4 years altogether. Do I speak Latin? Hell, no! I will get through a text in Latin when I need to, sometimes with a help of a dictionary, and that's all I need in what I need it for.
There's 9, and I don't think an average day has gone by in my adult life not using all 9 of those.
I assume that you are somewhat more educated than an average American and as such you'll certainly go beyond the bare basics on a daily basis and I'd be surprised if the 9 would be the only tenses in your vocabulary. Heck, I use more.
Of the 9 tenses a few won't be used as frequently, which is not to say they are unknown to most native speakers. All of them are very clear as to their meaning, once you explain it to a learner. Non-native speakers will be often aware of the English tenses they won't use. After all, "I finish this book tomorrow" covenys the same idea as "I will have read that book tomorrow".
Also, difficulties in learning English, or any other language, clearly stem from the learner's linguistic background. As others mentioned before in this thread, some aspects of a language are easier to learn, others are much, much harder to be retained. English is nowhere as difficult to a foreigner as Polish or a number of other languages. English is much more forgiving when to comes to minor errors. Of course the definition of "minor" may be debatable, but I'd argue that what can be construed as a minor grammatical error in English could render and equivalent Polish sentence incomprehensible. In the sentence, where the minor issue of inflection was neglected, what does this sentence mean (spelling incorrect on purpose).
zosia lubić jasiek.
Anybody non-native speaker?
A particular trait to America is the horrible way that they mix tenses in writing without rhyme or reason - and the worst thing is that it's practiced by educated people.
On a daily basis American English is not that complex, but as for the "educated" people, things will depend on what the term is understood to be. Are we talking about a PhD in English Lit. or an undergrad in phys ed?