I bet "s" in final position is much rarer than in typical text, because Wardle seems (reasonably!) to prefer base words over plurals, as well as past tense, participle, and other modifications.
For me the most useful immediate information is about vowels, making "adieu" quite useful. But "irate" and "inter" are also pretty good.
Most people focus on the yellow and green results, but the grey results can be even more informative. A grey result doesn't just tell you about its own position, but about all five. So each grey result from the first guess rules out huge swaths of the dictionary.
The more letters from ETAOIN SHRDLU you can cram into the first two guesses, the better off you are. Thus, any letters in color on the first guess would be wasted if repeated in the second word.
We all draw our lines somewhere different, of course, but to my mind, taking into account Wardle's specific choices as exposed in the source code feels like cheating, vs taking the full list of 5 letter words that his code "accepts".
Knowing what answers are actually "true" ahead of time is more information than I'm comfortable taking advantage of.
And yes, eliminating letters is crucial - in my opinion it's always better to guess 5 totally new letters for the second word.
I don't know anything about the source code, so cannot be drawing conclusions from it. Preferring non-inflected words is just good policy, for somebody running such a game.
For me the most useful immediate information is about vowels, making "adieu" quite useful. But "irate" and "inter" are also pretty good.
Most people focus on the yellow and green results, but the grey results can be even more informative. A grey result doesn't just tell you about its own position, but about all five. So each grey result from the first guess rules out huge swaths of the dictionary.
The more letters from ETAOIN SHRDLU you can cram into the first two guesses, the better off you are. Thus, any letters in color on the first guess would be wasted if repeated in the second word.