Yesterday, a customer gave me some cream puffs.

The package says "It's so crunchy that your gums will be surprise.d"

"gums" are considered plural. I guess people are thinking of the top and bottom separately?

"surprised" is the past tense of "surprise". It's kind of tricky with "will be" here as you're kind of looking backwards from a future point.

They don't usually use the word "gum" to describe a food on a package, but it kind of makes you want to try it.

It sounds like a very interesting

catch phrase/copy?

"copy" is a bit more detached, it's more something someone in marketing might say as they need to write several catch phrases this week. "catch phrase" is more natural here.

Yesterday, a customer gave me some cream puffs.

I'm guessing there was more than one in the packet, so here we'd use a plural.
If that wasn't the case, then instead of "some cream puff", you should probably write "a cream puff".
In the case that it was part of a single cream puff then "some of their cream puff" would make sense.

The package saysid "It's so crunchy that your gums will be surprised."

Generally when referring to your gums (歯茎) we use the plural - don't ask me why, but referring to it in the singular sounds wrong.
Since this took place in the past I'd phrase the sentence in the past tense.
Reading the original sentence someone might think "your gums will surprise what?"
Surprise is a transitive verb so the subject that goes before it surprises the object which goes after it.
Instead we would convert it into the passive voice (受け身). Thus it becomes "your gums will be surprised (by how crunchy they are)"

They don't usually use the word "gums" to describe a food on athe package, but it kind of makes you want to try it.

Since "package" here can only refer to the package that the food is in, we can use "the"

It sounds like a very interesting

"It sounds like a very interesting slogan".
"It sounds very interesting." would be fine on its own, but if you have another word after then you need to have an article (and the "like" also becomes necessary in that case)

catch phrase/copy?

I would usually call this a slogan
Catchphrase would probably get your meaning across, but it's usually used for a short repetitive phrase that's meant to be memorable.

It was definitely high in calories, but I ate it anyway.

Adding anyway here helps to illustrate the contrast. The original sentence is ok, but this way feels a little more natural to me.

Yesterday, a customer gave me some cream puffs.

The package saysid "It's so crunchy that your gums will be surprised."

TheyPeople don't usually use the word "gums" to describe a food on a packaged food, but it kind of makes you want to try it.

It sounds like a very interesting slogan

Yesterday, a customer gave me some cream puffs.

The package saysid "It's so crunchy that your gums will be surprised."

They don't usually use the word "gums" to describe a food on a package, but it kind of makes you want tona try it.

It sounds very interesting.

catch phrase/copy?

?

It was definitely high in calories, but I ate it.

Yesterday, a customer gave me some cream puffs.

It's "some cream puffs" if your customer gave you multiple cream puffs, and "a cream puff" if it's just one.

The package says "It's so crunchy that your gums will be surprised"."

or: "...so crunchy that it'll surprise your gums."

Gums (the organ) is almost always in the plural form "gums".

They don't usually use the word "gums" to describe a food on aits packageing, but it kind of makes you want to try it.

It sounds's a very interesting example of copywriting.

catch phrase/copy?