As a native speaker of a Slavic language, I know about foreigners trying (and sometimes failing) to use proper case for a situation, or using wrong gender declension, or an adjective non gender-matching the noun. Such sentence is technically wrong, but such mistakes does not prevent me to understand it (especially in a context), so it is not a big problem in the communication.
How important are correct tones to understanding a whole sentence (words in context) in tonal language? If I use mostly right tones, but use few wrong tones, will be native speaker able to decode and fill the right tones? Or even few wrong tones will make the sentence beyond comprehension?
Specifically I am interested in importance of tones (and recovery from wrong tones) in Thai language.
I found this question about tones in Chinese and obviously if a minimal pair is wrongly used in a sentence, it might make the sentence mangled beyond comprehension.
I know that learning proper tones of a tonal language is important. Are there some other possible strategies to deal with this problem? Or to make it less of a problem? Can I expect that natives will fill-in proper tones where I used wrong ones?