Is 「(Non-Past Tense Action A)前に(Past Tense Action B)」technically ambiguous?


From [How to appropriately pair tenses in subordinate and main
clauses?](https://japanese.stackexchange.com/questions/25376/how-to-
appropriately-pair-tenses-in-subordinate-and-main-clauses/25378#25378), one of
the answers provides:

> 歯を磨く前に食べた。

**Problem:** Is this sentence _technically_ ambigious, in that it could mean:
"I ate before I _brushed_ my teeth" OR "I ate before I _brush_ my teeth"? Note
that in second interpretation: (i) the brushing of teeth is in the non-past
tense, and (ii) it's ambigious whether or not the brushing has happened yet or
not.

The general pattern (if my understanding is correct) is

> (Non-Past Tense Action A)前に(Past Tense Action B)

could either mean

  1. **I did action B before I _did_ action A.** The usual/contextual interpretation.

  2. **I did action B before I _do_ action A.** Also technically acceptable?

**Question:** While I understand that, in context, interpretation (1) is
usually the more reasonable one, technically speaking is interpretation (2)
also valid?

* * *

**NOTE:** [IMABI's article on 前](https://www.imabi.net/before.htm) provides
examples in which interpretation (1) is exclusively chosen. For example:

> 私は旅行に行く前に、トラベラーズ･チェックを買いました。
>
> I bought traveler's checks before **I went** on my trip. (Couldn't this also
> be "before I _go_ on my trip")?




I would argue that neither of those interpretations is actually technically
the most accurate/direct translation into English, and instead that (non-past
action) + 前に actually has basically the same meaning as using the _gerund
form_ ("before (verb)ing") in English:

> 歯を磨く前に食べた -- "I ate before brushing my teeth"

In this sense, I think it is really exactly as precise or ambiguous as this
English sentence is. It says that the time you were eating was chosen so that
it would be before you brushed your teeth, but does not say anything about
when the brushing of the teeth might have happened or happen. The strong
implication is that brushing teeth would occur shortly after eating, though,
and therefore if you ate some time ago it is assumed that you have already
brushed your teeth by now.




I would argue that neither of those interpretations is actually technically
the most accurate/direct translation into English, and instead that (non-past
action) + 前に actually has basically the same meaning as using the _gerund
form_ ("before (verb)ing") in English:

> 歯を磨く前に食べた -- "I ate before brushing my teeth"

In this sense, I think it is really exactly as precise or ambiguous as this
English sentence is. It says that the time you were eating was chosen so that
it would be before you brushed your teeth, but does not say anything about
when the brushing of the teeth might have happened or happen. The strong
implication is that brushing teeth would occur shortly after eating, though,
and therefore if you ate some time ago it is assumed that you have already
brushed your teeth by now.

