It's pretty much the same thing.
All the bodyshops I know just buy 25 ltr drums of standard thinners to use as gunwash because it's the cheapest stuff available.
Might be different in smaller quantities
Cellulose thinners to get the 'dirt' off and then panel wipe/degreaser to leave a clean surface to paint on.
I put my panel wipe in a spray bottle, spray an area,wipe it off with generic blue paper towels,throw away and repeat.Don't leave it to evaporate
Remember if you are using a hvlp gun you'll need large bore hose and fittings from the compressor.
Many people don't which is like having a 4k tv but only watching SD channels on it ie you won't actually be watching 4k tv
Definitely do NOT sand the basecoat and then spray clear on it.
DO buy some more basecoat,scuff it,spray more basecoat and then clear it...... I wouldn't even leave it overnight before clearing but i do understand that for custom work it can be unavoidable
I found this site.
I don't know how good they are but there's some good info regarding colour matching
https://www.carcolourservices.co.uk/the-colour-matching-process/
I've been using it wet on wet recently Dcal,epoxy, leave it an hour and then on with 2k primer.Not had any issues so far.
So yeh,in the OPs case get the seam sealer on as soon as and recoat as soon as that's dried would be the easiest way.
When I used PPG epoxy you had a 24 hour window to recoat before sanding was required.
The Lechler data sheet doesn't say how long you have which is a bit odd,just says you can sand after 18 hours.
If it were me I'd scuff it with a red scotchpad just to be on the safe side.
Well if it's mixed to the code that's not colour matching is it.Some codes can have multiple shades,in fact most do,i think 8 is the most I can recall for a single colour code.
Plus a vehicle is likely to have been painted at some point,often multiple times,with different manufacturers paint...
I don't like Mipa products at all,cheap for a reason.
One clear i used to use a lot was upol 20:80.....always flowed well and gave a nice flat finish without running like some clears are prone to doing when not used in a heated booth