Colourless mana in mana pool-to converge like abilities

[Aswan jaguar]

I don't know if we have discussed this before but the engine will always use all available colourless mana from mana pool to pay the colourless cost of a spell which I guess is a feature of auto-cast? This causes problems at times with some abilities like converge - Roilmage's Trick, sunburst - Etched Oracle and you can't use the coloured mana in mana pool.
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