I've been working from this recipe - Ricetta Lievito madre - La Ricetta di GialloZafferano
I made a few modification based on what was available. So Instead of Farino 00 and Farino Manitoba, I started with Whole Wheat flour because it was unused and going to waste so I thought I might as well use it up to make the starter. My plan was to slowly at each feeding to reduce the amount of whole wheat flour while introducing bread flour into the mix until the whole wheat flour was eliminated.
Everything else was as in the recipe including starting with the blended soaked raisins and feeding every 48 hours.
I also cut the recipe in half at subsequent feedings to reduce waste.
My problem is that the starter smells so bad like acetone / nail polish remover. So strong. Then at my recent feeding today the surface of the ball of dough had formed what looked like mould (fuzzy stuff) all over it.
It was at that point that I tossed everything in the garbage.
I started April 19 and ended today (April 25) so that was only 3 feedings/refreshments.
Honestly I'm thinking of going back to 100% hydration starter for regular sourdough because that is the only successful starter I have ever made. Every time I try to make a 50% hydration starter it ends badly.
Did your raisins have sulphur dioxide on them? If so, that might have had an effect on fermentation. Although it is an interesting idea to use raisins, since grape skins naturally have yeasts on them.
Any regular sourdough starter can be used to make lievito madre. It does take time though.
Le fermentazioni spontanee by Di Cristo, Marinato et al, is an interesting book on using non-flour ingredients in starters. I have not had a lot of luck with this approach, and my LM is just flour-based.
Otherwise, Hamelman has a raisin based, 63% hydration starter in his "Swiss farmhouse bread" recipe that could be worth investigating?