I think you should add a note. Cause the other day I went to practice my Czech with my good Czech friend and when I said "Jedí" She had to take a moment to get what I was saying cause she told me no one ever says this anymore and they often will say "jí" instead.
this is from the food tips, which is where both jedí and jí are introduced:
Note that the only standard form for the 3rd person plural jedí is a source of trouble for many Czechs, who incorrectly think that it should be “jí“. (One day it may become acceptable in the standard, but we are not there yet.)
1) We teach Standard Czech, that is, the codified form of the language.
2) We do not teach any dialects or interdialects.
3) The only possible form of jíst in 3rd person plural is jedí.
4) The Tips and Notes sections are limited to 5000 characters. We have trouble explaining the most basic things within this limit. There's no chance of including every possible variant of sloppy speech.
5) Tell you friend to learn to speak properly.
6) Don't believe everything someone told you. ;)
I use that word "JÍ" too (just like most of the native CZE speakers), but - I can imagine a conversation - on a noisy street:
- "Co dělají?" (what are they doing?)
- "Jí" (they are eating)
- "Co?" (what?)
- "ONI JÍ" (THEY ARE EATING)
- "COŽE? Co JÍ dělají?" (WHAT, what are they doing to HER? ("jí"=her))
- "Oni JEDÍ" ("jedí" - 2-syllables are more understandable)
- "Aha, proč jsi to neřekl hned" (I see, why did not you say that before?) :-)