It’s all good. If you’re using bash and readline to read the file, you can use sudo echo ${INPUT@Q} (assuming your variable is named $INPUT) to have bash escape things like the quotes and other characters that could get you into trouble.
Sadly no, its injected with terraform templatefile, I already looked for a normal way to autoescape it, but from a brief look I couldn’t find one. I know there is a replace function that can take regex(RE2, which from my understanding prohibits * in lookbehinds)- but the simplest regex I could think of at nearly 6am for capturing only non-escaped quotes is /(?:^|[^\\])(?:(?:\\\\)+|[^\\]|^)(?'quote'")/gm. Though, I just realized if the quotes are escaped I would want to double escape them, so actually replacing all quotes with escaped quotes should be fine, also another limitation of this method is lines can’t have trailing \