No "if-then" in the original sentence.

suli ala la
-> suli ala tan ni la
-> suli ala ni:

noka (to kick?) -> jo

There is still no if-then in the original sentence, though. (Nothing like "If this box isn't heavy, I can carry it.")

@Yanqui

poki ni li suli ala. (tan ni la) mi ken tawa e ona kepeken luka.

@Biderl
"tawa e ijo kepeken luka" for "carry" is nice, but there is already "jo" for that. (Besides, "moving" doesn't imply "lifting". One might think of a box being dragged away.)
In your proposal, "enough" is missing.

I'm using "la" is a context indicator, not a conditional. The box can only be carried in the context that it is light - using la explains the ability to carry it, just like "light enough" does in the English sentence.

toki!

jo e ona -> tawa e ona [?]

Carrying doesn't necessarily imply moving, and "carry" is one of "jo"'s meanings.

> I'm using "la" is a context indicator, not a conditional.
Yes, I should have said "no if/when-then", right?

> The box can only be carried in the context that it is light - using la explains the ability to carry it, just like "light enough" does in the English sentence.

I don't understand your wording here. First, "in the context that" *is* "if/when", isn't it? Is "in the context that" anything else than "if/when" that I'm missing? I understand and agree that "poki ni li lili la" means "(only?) in the context that this box is light" (or "if it is light", for short).

The point is though, that in Toki Pona, "la" doesn't say if the context is given or not, whereas in English, "the box *is* light enough" expresses that the necessary context is given. So the original and the translation don't match.

Also:
mi -> jan li

In my experience, "la" can also be explanatory, not just speaking of general situations. "sina kama weka la mi pilin ike" = "You left, so I feel bad." Although, yes, there is ambiguity here, that's a natural part of Toki Pona, and I think replacing it with a tan phrase would make it unnecessarily clunky. Toki Pona is meant to be clear in context, and if you're carrying a box and saying "poki ni li lili la"... it's clear that the context phrase is true.

I understand when you say that you use "la" for "so". Like linking two sentences together with "so". I have seen that, too, but I consider it wrong, since I have no source (course, book, etc.) that backs this usage. I know "if/when A then B = A la B", but I don't see that this can be extended to "A so B". Toki Pona has "tan ni (la)" for this.

You left, so I feel bad.
sina tawa weka. tan ni la mi pilin ike.
mi pilin ike tan ni: sina tawa weka.

If you leave, I'll feel bad.
sina tawa weka, la mi pilin ike.

Of course, you can say

You left. I feel bad.
sina tawa weka. mi pilin ike.

But that's another story / translation.

lili = light
-> lili pona = light enough

I'll have to think about it. Maybe there is another way to avoid "tan" here.

Everyone's Toki Pona is different, and experimentation is encouraged. As long as the meaning is transferred properly, does it really matter?

> Everyone's Toki Pona is different
Tell me about it! The eternal struggle between order and chaos - from the point of view who's trying to maintain a corpus. Who's going to win? Philosophy aside, mind that I'm trying to be descriptive, not prescriptive. There are many known ways ("nasins"), but when there is a new one coming up, or a new combination of nasins, I have questions. It matters in order to maintain the Toki Pona corpus. For you as a user of Toki Pona, it doesn't matter, I grant you that. But since you're contributing to the Toki Pona corpus, the context is a little different.

If you would change "lili" (light) to "lili pona" (light enough), we can make this work with the following nasins/tags:

This box is light enough to carry.
= poki ni li lili (pi) pona ni: jan li ken jo e ona.
= poki ni li lili pona. tan ni la jan li ken jo e ona.

[Tepan]
= tan ni: poki ni li lili pona, la jan li ken jo e ona.

[lipu ku - topic marker]
= ni: poki ni li lili pona, la jan li ken jo e ona.

[lipu pu]
= poki ni li lili pona, la jan li ken jo e ona.

[lipu ku - punctuation]
= poki ni li lili pona la jan li ken jo e ona.

I don't see the need for "pona" here. The "la" implies the "enough" part.

Well, at least I tried.