I am not sure why you feel it more consistent to use "English derivatives" all the way. Does it mean that, if you have an English-derived word in a sentence, the whole sentence should be made using only English-derived word? I think it is much better to read it in Japanese reading.
When reading mathematical variables or chemical formulae, often, non-specialists tend to read the subscripted number in English-derived reading if they are small enough. For example:
But when the number is large enough, or if the reading becomes complex enough, they switch to Japanese reading:
This is stupid. Probably non-specialists do not have enough knowledge to read large numbers in the English-derived way, but nevertheless do so for small numbers, and do not think about inconsistency. On the other hand, people with enough consideration do not pronounce it in an inconsistent way but read the numbers in the Japanese way regardless of the size of the number.