Pluralization of "XX Second Delay"

There is an app that I recently used that had music playback functionality. Among other things, one of the features it provided was that I was able to adjust the speed of the lyrics using two buttons. However, I have marked the following irregularities in its prompts:

As I press the forward button repeatedly, the following is shown:

0.5 Seconds Early
1.0 Second Early
1.5 Seconds Early
2.0 Seconds Early
...

However, when the reverse button gets pressed, the prompts are as follows:

0.5 Second Delay
1.0 Second Delay
1.5 Second Delay
2.0 Second Delay
...

As we can see here, the pluralization of "second" is simply not used for the "second delay" phrase(if this be a phrase). I have wondered whether this is a mistake on the translator’s part or that this is indeed some obscure grammar where "seconds delay" would actually be wrong in this context.

I know this app is translated and not developed by English-speaking people, but this is the EXACT REASON that I am a little unsure of myself. If this app were made by English natives, this could, with a high chance, be a grammatical error since native people generally don’t know the grammar of their own language well. On the other hand, professional translators will rarely make any grammatical mistakes, since they must have studied the language well before obtaining whatever licence that may be required.