I I’m low level and have not much clue but I see that only the particle is the change so shouldn’t the difference be only in a sentence? Again, I’m not advance so I have no clue but maybe..?
The sentence itself is a bit off. You'd be understood, but it's quite unnatural. Having まだ + 僕でも at the start like that is the main issue.
Besides that, all 3 particles are possible, but が fits best. It's the natural choice when talking about your "ability" to do something. は is the usual "contrastive" nuance. "As for Japanese..." (as opposed to whatever else there might be). And を is the weakest option.
Note: Not to be confused with を + 話します, that would be very different.
Edit: To be clear, I don't think there's anything grammatically wrong with your sentence, it's just clunky. I'd probably say 僕でもまだ日本語が話せません。
Edit: Oh, and one more thing—with が and を the meaning is pretty much the same, while は adds it's own contrastive nuance. Here's a quote from a native speaker: "『僕は日本語は話せない』sounds like it implies "I can't speak Japanese, but can speak another language".
My teachers told me that with the potential form it's incorrect to use the particle を. Using は is like saying that you only can't speak japanese, but you could use this particle in "日本語は話せませんが、英語は話せます". In your case I would use が
My teachers told me that with the potential form it's incorrect to use the particle を. Using は is like saying that you only can't speak japanese, but you could use this particle in "日本語は話せませんが、英語は話せます". In your case I would use が
The reason why I called を the "weakest option" instead of "incorrect", is because in practice a lot of Japanese people don't seem to have a problem with it. I understand why a teacher would classify it as "incorrect" though. That's reasonable.
For example here's three natives not flagging を + potential form [Source]. My guess is it has to do with Textbook usage vs Spoken language. It's technically "non-standard", but since it's common enough in real Japanese, many natives don't perceive it as wrong anymore.
Saying "Textbook usage vs Spoken language" might be an oversimplification on my part. There are probably other reasons for why を is sometimes acceptable.
You can also find a voiced sentence that does this on Renshuu itself, e.g. 私は間違わずに英語を話せない。
Just thought it was an interesting phenomenon, I also think が is the most "natural" choice :)
PS: 話す → 話せる = potential (can speak). Just in case anyone is looking at autogenerated conjugation tables, this line is wrong - Potential 話せられる 話せられない, that's a "double" potential, it's not a thing...
I would've agreed to the sentence saying, 「僕でもまだ日本語X話せません。」But it's obviously not about what's a grammatically correct arrangement, since this is not a major deal and that properly attached particles are the ones doing the heavy lifting to dictate how you want to say things. The trouble is the は/が/を choice.
It doesn't seem meaningful to use は in this instance, unless you're implying something that you're contrasting with the statement. It is likely more distinctive to use が. を is a bold choice to state something so matter-of-factly, but I don't see the point of using that tone in that statement. You could, if there was a point to it.
However, I found something interesting : ~It is not used with particles such as が, を, and は, but it can be seen after other particles such as に, と, から, and まで. However, in slightly older Japanese, you can see combinations such as ～をでも. It is not advisable to use this as it is, again, not used anymore. The Particle でも -IMABI今日
