I see your code using regexes and it is more concise for this kind of parsing. When there are well defined separators I automatically go for String.split which is more verbose.
Anyway this was easier than day one 
defmodule AdventOfCode.Y23.Day2 do
alias AoC.Input, warn: false
def read_file(file, _part) do
Input.stream!(file, trim: true)
end
def parse_input(input, _) do
Enum.map(input, &parse_game/1)
end
defp parse_game("Game " <> game) do
{id, ": " <> rest} = Integer.parse(game)
hands = rest |> String.split("; ") |> Enum.map(&parse_hand/1)
{id, hands}
end
defp parse_hand(txt) do
txt
|> String.split(", ")
|> Enum.map(&Integer.parse/1)
|> Enum.reduce({0, 0, 0}, fn
{n, " red"}, {r, g, b} -> {r + n, g, b}
{n, " green"}, {r, g, b} -> {r, g + n, b}
{n, " blue"}, {r, g, b} -> {r, g, b + n}
end)
end
def part_one(problem) do
problem
|> Enum.filter(fn {_id, hands} -> Enum.all?(hands, <e?(&1, {12, 13, 14})) end)
|> Enum.reduce(0, fn {id, _}, acc -> acc + id end)
end
def part_two(problem) do
problem
|> Enum.map(&power/1)
|> Enum.reduce(&(&1 + &2))
end
defp lte?({r, g, b}, {max_r, max_g, max_b}) do
r <= max_r and g <= max_g and b <= max_b
end
defp power({_id, hands}) do
{r, g, b} =
Enum.reduce(hands, fn {r, g, b}, {min_r, min_g, min_b} ->
{max(min_r, r), max(min_g, g), max(min_b, b)}
end)
r * g * b
end
end
)
