I continuously confuse these/those/the in connection with to/ty/ti... is there a rule (of thumb) or a hint how to remember correctly?
A quick way... When you see -to or -hle attached to a demonstrative (ten, ta, to, ty, ti) you can pretty much count on its meaning being "this" or "these." Without the suffix, the translation is generally "that" or "those."
Proč nelze překlad These are big machines. chápu those pro ukazování na vzdálené předměty, these ukazování na blízké, ale tady není vzdálenost známá, tak lze zaměnit
The sentence is literally "Those are big machines." Your suggested sentence would be slightly different -- Ty mašiny jsou velké.
Is there any major difference between using "To" (as in the example) versus "Ty"?
Yes, in the sentence pattern "to jsou/jsou to" you always use TO. On the other hand when saying "the machines" you use "ty stroje".
This is the very often used to je/to jsou construction. It is generally translated as "it is/that is" (for to je) or "they are/those are'" (for to jsou).
this is one of the biggest problems i have with this course. "to" is something you point at, it's not specified whether it's close or far, like with "this" and "that" which is why literally everyone in here, including me, thinks both forms should be accepted
It will take a native CZ speaker to explain the nuances, since I don't entirely understand them either. My personal "working rule" is: If the demonstrative pronoun stands alone, I go with "the" or "that." If it has -to or -hle tacked on to the end, I use "this." BUT... if there are both tam AND hle as part of the word (e.g., tamhleten), I revert back to "that." This seems to work pretty well, but I'm always surprised when "this" turns up as an acceptable alternative when I've used "that." Maybe it's something that just one day unexpectedly falls into place, after enough exposure. You might also have a look at this discussion... https://forum.duolingo.com/comment/30017389$from_email%3Dcomment&comment_id%3D30461871
Can anyone explain why or the logic of conjugation of the word machine?
How does it go from "stroj"(s.) to "mašiny"(pl.)?