I'm sorry that you're taking offense; that's not necessary at all. My point about the slide show is because several posters have set their photos up this way lately and I'm getting dizzy :-) It's a form of technological advance that does not help.
There are two issues at play here. One is that if you are asking people for advice, they need a certain amount of information. Most of the people here are pretty conscientious - even if, like me, we're not professional landscapers, we are pretty careful not to give advice that can make situations worse or create further problems. In order to to maintain that standard, we need to understand the problem thoroughly, which includes having good photos and being able to study them, and in this case, the second issue: understanding why this problem was created in the first place. And it was created - you may believe that there were no obvious drainage issues until you started getting heavy rains, but water flows downhill and you've said you have clay soils (and now a high water table). As such, any builder, landscaper, or engineer who was involved should have foreseen that water flow from your neighbour would be a problem, among other issues. But sometimes the construction choices made were made for good reason, and it helps us to understand what those reasons were - for instance, you've pointed out that the drop-off was initially much worse. The fact that you don't have a basement is also important information, because the pictures don't tell that - is it a crawl space then - or something that does not need to be kept dry?
The other thing we need in order to be helpful to you is feedback to what we say and also answers to whatever additional questions we feel we need to ask. You have responded on some issues, but not on others. My point as to whether the gutters can re rearranged to discharge to the back of the house stands unanswered, and it's also not clear to me whether that would help because the video doesn't show the water pooling as clearly as you might expect it to. As does the question of what professionals you have consulted so far, and what their views have been.
The possibility does exist, and we've seen it here before, that your house was very poorly sited and that litigation might be more suitable than mitigation. You've stated pretty clearly that you do not think that's the case, but I hope you can appreciate that based on what you've shown and how you've described the water issue, the average observer would be led to think in that direction.
I hope you'll engage further so that we can understand your problem better. Even if you do end up needing professional consultation, people here may be able to help establish the range of options or questions you should ask.
KarinL
PS: for me in particular I am always concerned that I not contribute to a situation like the one that set up a tragic mudslide in my area a few years ago. Story linked below. Not that you have houses below, but I wouldn't want to hear of your house taking a slide either.
Here is a link that might be useful: North Van mudslide story
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