We’re all pretty familiar with Roman numerals, but when talking aloud about numbers, did Roman language mirror their numeral system in some way, or were the numerals distanced from the spoken way that numbers were communicated in their culture?
They pronounced them, just like every other language. I don't have the patience to futz around with reddit's stupid formatting, but: ūnus, duo, trēs, quattuor, quīnque, sex, septem, octō, nōvem, decem (for 1-10). They denoted tens with a -gin element, so 20 was vīgintī, 30 was triginta, 50 was quīnquāginta, etc. 100 was centum. Like the Romance languages which derived from Latin, the Romans counted [edit: 'counted from 1-7 after 20 using additive language, "twenty and one" or "thirty and four", but Latin switches to using "one from" for numbers after seven']. Thus 79 was ūndēoctōginta, "one from 80." Everything else is a variation of the above. The number 2021 is duo mīlia vīgintī ūnus (mīlle is 1,000 in Latin, not 1,000,000).