Seals are not that hard to replace, and you don't necessarily have to replace them with the your specific brand factory originals either. More than likely, the previous owner closed up the tent ends when the canvas was still wet and it never had a chance to dry out completely before closing up. Thus, the musty smell.
A good airing out, a bit of soap and water and a good dry-out will get rid of the musty smell.
But, here is the problem with hybrids and tent-pop-up campers... if they are closed up wet, they are prone to molding, musty smells, and dampness that filters through the entire camper.
Personally, I would never have a hybrid for this very reason. When we had our pop-up, it seems we were always (and I mean "always") were forced to break camp in the rain or right after a rain, and never had a chance for everything to dry out first. Luckly, we could bring it home and set up back up in the drive way to finish airing out. However, if it was a continuous rain over several days (which is not uncommon in Indiana), the camper would have to sit in the drive way opened up for days before it dried out enough to close it up. By then, we were ready for the next week-end outage!
Eventually, I realized I could pull the pop-up in the garage and open the top about 3 feet and let the canvas hang over the outside of the camper, allowing it dry over night, which we did a lot. Once dried, then I could close it up tight. It was especially important in the fall, when putting the camper up for the winter to make sure it was completely dry. After our first winter, (the next 5 winters), I'd let it dry in the garage almost 2 weeks before closing it up final, just to make sure it was truly completely dry.) Meanwhile, both cars sat outside in the miserable weather.
Our first winter with the camper, I didn't realize it was still damp and it was closed up. Come Spring we had mold everywhere. Lesson learned.
Bottom line, there are some folks who say they never have problems with packing up hybrids with wet canvas. And probably they do just fine.
BUT ... it is quite obvious, THIS camper you are considering does not fit their experiences.
I think getting the seals replaced is no biggie, and I think cleaning the musty smell out is no biggie. But ... you now know the vunerability of the camper. You cannot close this one up wet. You can't.
Your choice? How much work and effort do you want to put into keeping it dry when breaking camp on a dew driven morning, or in a deep forest where it's just naturally very damp any time, day or night, or season of the year, or during a rainy spell? If you feel confident you can deal with then, they THIS SPECIFIC camper will be OK for you. Only YOU can decide how much effort you want to put into it.
We didn't want to deal with canvas any more after 6 years of pop-up experience. We went with a hard sided travel trailer next, and have never regretted that.