うな重が食い逃げした does not seem that crazy to me. It is no different than English speakers saying some variation of “it grew legs and walked away”. Usually, that is hyperbole to make a reduction ad absurdem argument about someone stealing. The Japanese phrase interestingly illustrates a use of “ga” (が) as a subject marker, which among other uses, is used that way when reporting new information.
That said, 私は美味しい illustrates how you really need an entirely different way of thinking about language in order to understand Japanese. If you want to report you are tasty as an English speaker might misread that upon hearing は is a subject marker, you would want to use “ga” (が) to mark what is being described as tasty. If you bizarrely want to say you are tasty, like how an English speaker would interpret that upon hearing は means subject, you would want to use が instead of は.
In a slightly more normal but still quite bizarre situation, if you wanted to say you are not tasty, you would say 私が美味しくない. That would be useful if you wanted to tell a Japanese speaking cannibal that you are not tasty. It also would look extremely weird to an English speaker in comparison to the version that declares yourself to be tasty, since two characters were added to the end of tasty to negate it, unlike English where “not” is added before the adjective, but that is how Japanese works.
うな重が食い逃げした doesn't make sense at all. It literally only means that eel over rice itself ate something and fled away.
I think GP meant うな重は食い逃げした. This sentence can be interpreted as the same as above or "[the person] ate eel over rice [but not other dishes] and fled away".
It says that the grilled eel over rice dined and dashed. It sounds like a euphemism to me. It is not very different from saying the grilled eel over rice developed legs and ran away. In either case, you are suggesting someone stole it.
As a Japanese person, I can confidently say that うな重が食い逃げした sounds nonsensical to Japanese ears. The verb 食い逃げ means the subject (うな重 in this case) ate something, not the other way around. Regarding euphemism, you could instead use expressions like うな重が消えた ("うな重 vanished") or うな重が旅立った ("うな重 set off on a journey") to metaphorically describe someone eating their meal.
But... come to think of it, even a native speaker may not be in a position to deny someone's finding about interesting similarities between Japanese and English sentences and possibilities of interpretation.
I just realized the example might have had a typo like you said. It is an interesting typo since it reminded me of a similarly absurd expression in English. When the expression is used in English, the entire point is to be nonsensical such that the only resolution is that someone moved/stole something.
As I am still learning, I have been trying to be open minded about possibilities. That helps when encountering things like 風邪です and 空気がおいしい. The former as you know literally means wind, but also can mean having a cold (and it would be very socially awkward if someone’s name was 風邪). The latter literally calls the air tasty, but means the air is fresh. The downside of being open minded is that someone can tell me something wrong and I will try to interpret it under the assumption that it is correct.
That's interesting, because I took the sentence verbatim from a linguistics book (辞書には書かれていないことばの話、仁田義雄). It says うな重 is short for 「うな重を食べた人」. It was compared with 漱石を読んだ (-> 漱石の作品) and 及第点に荷物を持たせよう (-> 及第点を取った人)
So you're saying that this sentence makes no sense unless は is used?
That said, 私は美味しい illustrates how you really need an entirely different way of thinking about language in order to understand Japanese. If you want to report you are tasty as an English speaker might misread that upon hearing は is a subject marker, you would want to use “ga” (が) to mark what is being described as tasty. If you bizarrely want to say you are tasty, like how an English speaker would interpret that upon hearing は means subject, you would want to use が instead of は.
In a slightly more normal but still quite bizarre situation, if you wanted to say you are not tasty, you would say 私が美味しくない. That would be useful if you wanted to tell a Japanese speaking cannibal that you are not tasty. It also would look extremely weird to an English speaker in comparison to the version that declares yourself to be tasty, since two characters were added to the end of tasty to negate it, unlike English where “not” is added before the adjective, but that is how Japanese works.