Assuming you are familiar with all relevant languages/frameworks involved then reading other people's code is not hard at all if 1) you understand the purpose

Assuming you are familiar with all relevant languages/frameworks involved then reading other people's code is not hard at all if 1) you understand the purpose of the portion of the code base you are in 2) you understand design/architecture of that portion of the code base and 3) You ask for a quick overview from someone. Yes, sometimes code is loaded with all kinds of indirection that usually comes from OO programmers outsmarting themselves with all kinds of implicit polymorphic dispatch and unnecessary design pattern legacy. This is why its important to ask someone familiar with the code to give you a rundown.