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I do understand the confusion and "Target" does need tighter usage and clarification in general, and Sequester's spell description could explain that targets become Immune to Divination magic or effects but that's not what it says.

I would deal damage just as I would see the Sequestered item.

I do understand the confusion and "Target" does need tighter usage and clarification in general, and Sequester's spell description could explain that targets become Immune to Divination magic or effects but that's not what it says.

I do understand the confusion and "Target" does need tighter usage and clarification in general, and Sequester's spell description could explain that targets become Immune to Divination magic or effects but that's not what it says. It's fairly ambiguous as it is.

I do understand the confusion and "Target" does need tighter usage and clarification in general, and Sequester's spell description could explain that targets become Immune to Divination magic or effects but that's not what it says.

can be hidden away, safe from detection for...

This doesn't say "detection magic" or spells, nor does it literally mean it cannot be detected entirely (you can still detect by touch for example). It's fairly ambiguous as it is.

Closer look at why Sequester is not the target of see invisible/detect magic

Scenario:

I am fighting a monster immune to attacks from non-magical weapons that cannot be targeted by spells, I cast magic weapon on my sword and then hit the monster, do I deal damage to it?

Is the monster now the target of my magic weapon spell? I don't think so, as per the spells' description I can't target the monster with "Magic weapon" nor can I target an (in)visible object with "see invisibility".

I do understand the confusion and "Target" does need tighter usage and clarification in general, and Sequester's spell description could explain that targets become Immune to Divination magic or effects but that's not what it says. It's fairly ambiguous as it is.