You’re not overthinking it but maybe overdoing it.
The eiswein is not fortified. It’s very syrupy and while I haven’t had the 1998, that’s almost twenty years ago so it may be picking up some caramel notes to go with the citrus and petrol that those have when young. It is usually extremely low in alcohol, usually under 7%, and really high in both acidity and sugar. In fact, while I don’t know the sugar level of that particular one, it will have the highest sugar content of all your wines.
The Clos Solène Sweet Clementine is a sweet, young, fortified wine that would probably have been fairly sweet and ripe to begin with, even without the fortification. It may seem less complex than the eiswein, but it will also have more of an alcoholic burn. And it may have some tannins. I’m not too familiar with that specific one but they do make fortified Grenache in Spain and France and I’ve had plenty of those.
The tawnys are going to have around 100 g/l sugar as well. I think the Graham’s is actually a little bit higher, but I can’t say for certain. It usually tastes a little sweeter. They’re both going to be fine, with nice caramel/toffee notes that work wonderfully with nuts, sharp cheeses, cured ham, and even, although I hate to say it, chocolate. I don’t think chocolate should ever be served with wine and have no idea why people keep trying to push that pairing, but if you’re going to have anything, it should be a tawny.
The eiswein can have maybe double the sugar of the other three and it won’t have the alcohol. I wouldn’t serve it with any dessert and I would let that be the dessert. No food is really necessary.
For me, a fortified wine after a non-fortified dessert wine always tastes clumsy and overbearing. So long ago I swore I would never have the two together. I used to open aszu wines and a friend would insist on bringing fortified wines and it’s like listening to Mozart and having someone come in playing heavy metal. So it’s not like one will be underwhelming as much as awkward.
On their own, the fortified wines can be delicious and they do pair with different foods.
If you’re not going to finish them, I’d rather have a half bottle of tawny left than a half bottle of the other two. Good luck!