Okay, let's go over a few issues that have been raised:
The number of elves in the Dales. Most Andrastrian elves are confined to the city in alienages. They aren't allowed to move around without permission. In the majority of cities the number of humans is greater than the number of elves. However, in Halamshiral the opposite was true. There were more elves than humans and apparently they weren't confined in an alienage, just outside the old city proper. The reason the uprising was so dangerous was because of the number of elves involved and other elves were ignoring the restrictions and rushing to join them. The reason the elves were unable to take the city over completely is that on the whole they only had makeshift weapons and armour, whilst the city guard was fully armed. So the ruler decided to dig in and defend the nobles' area behind the city walls proper, leaving the elves to pretty much run things in their own part of the city. When Celene decided to put down the rebellion, she marched in, massacred any who tried to stand up to her forces and then burned the rest in their homes. So at this point there would have been a considerable drop in the number of elves present in the Dales. Hence not encountering many outside of servants and a few out in the countryside. Even if they hadn't been burned by Celene, most elves would have been in Halamshiral and other cities and we never visit any of these except a very small section of Val Royeaux.
Another fear of Celene in putting down the rebellion was that there were hidden enclaves of Dalish just waiting for the opportunity to rise up and reclaim their homeland. Briala might have been angry at the reaction of the Keeper to her assumption that the Dalish ought to have helped the city elves but as Celene realised, even if the Dalish want to help, they didn't have the numbers to do so. Based off what is said in the book I would judge there are probably more elves in the alienage in Val Royeaux (10,000 according to DAO) than in the Dalish clans in the Dales and if they had attempted to aid the rebellion in Halamshiral, they would have been wiped out as well. The majority of the Dalish actually live outside the Dales, with the biggest concentrations in Ferelden and to a lesser extent the Freemarches.
As for Abelas using the word Shemlen to refer to the entire party. Considering he doesn't even consider the Dalish are his People, it is likely that he looks upon all races as "Shemlen". Varric or the Inquisitor would be the only dwarves in the party and surface dwarves, so if the dwarves of his time considered that dwarves on the surface were not "Children of the Stone", then possibly Abelas does too. Hence being lumped with humans and modern elves as Shemlen. Mind you, I'm surprised he doesn't query the appearance of a qunari Inquisitor, so is this meant to suggest that he knew of their existence or he is simply not that bothered about modern races? Probably the latter but who knows.
In Trespasser the elf in the Deep Roads recalls an old Dalish lullaby that his mother used to sing. It is said to be about Mythal but the elf notices the possible link with the dwarves in translating it and makes the connection with the statues of Mythal in the Deep Roads. Clearly the Dalish weren't aware of this link and were just passing down an old song without really knowing its significance. He even says that his Hahren had told him that they had lost some of the old words from the song. If that is the case, then the word used "Durgen'lin" (Little stones) probably was originally "Durgen'len" (Little dwarves), giving the clear link and reason why Solas refers to Varric as "child of the stone". Although, of course, this never seems odd considering the dwarves themselves speak of their connection to the Stone. Still, I think it is clear that in the time of the ancient elves, the dwarves were referred to as "Children of the Stone", possibly even given that title by Mythal herself, so Abelas would definitely consider that title appropriate if he encountered dwarves underground but, as I say above, probably not when he encounters them on the surface.