There are a handful of abandoned x86 VST2 plugins that I really like - the entire Kjaerhus collection comes immediately to mind. And in fact I think that may be the last of them. And I am pretty sure they will never be updated, so I continue to look for alternatives.
In the meantime, if a developer is still actively developing then I expect them to come up with an x64 version of their plug-ins... heck, I kind of expect them to come up with a VST3 version<G>!
It takes time, I understand that, I spent way too much time developing commercial software!
And it is not something that can be easily scheduled. You might think you'll have it done by a certain date, but until it is done you never really know. I understand that too.
But I also understand that ANY bridging trick is just that, a trick. And it should be used carefully, and cautiously, and sparingly. Some here probably remember the VST to DirectX bridges, one of which Cakewalk did buy. They had their problems too. And eventually most of us abandoned any plug-in that did not come in a VST format.
Frankly, if I paid any amount for a plugin I'd be asking the plugin developer to fix the problem, I would not be depending on a trick to get me by. Focusrite is a pretty upstanding company - I'm pretty surprised they have not updated it. But if they haven't, and if they have no plans to do so then you do have a big problem.
And I do sympathize!!! There is NOTHING more frustrating than losing the use of a software tool for which you paid good money, in good faith. Sadly, there are quite a few software developers that do not think they have any responsibility to their customers. The equivalent of the age old "trunk slammer". And most of us will get burned by one of these clowns at least once.
Anyway, if you are using this as a hobbyist then you are probably stuck. If you are using this professionally then I'd take a look at what income you have earned as a result of owning LiquidMix, and writing it off as a lost cause if possible. Not fun, pretty distasteful in fact, but probably necessary. Sorry!