I don't like spicy (meaning hot) food at all and have some difficulty at Jiko. I also can't eat cilantro. I always ask "is it spicy" and ask about cilantro and if they say a little, I ask how spicy etc. But the servers are very helpful and you can still have a delicious meal there. They will be honest and tell you what will work. There have been a few times that I thought something sounded like it would be good for me but was then a little to spicy for me - in particular there was a delicious flat bread that turned out to have a sauce on it that had more heat than I can really enjoy.
When you say you don't like spicy - if you mean hot - you will still be able to enjoy your meal. But if you mean you don't like the flavor of a lot of spices, Jiko may not be your best choice. It is not that you won't be able to find something you will like, but it is expensive and other signature restaurants may be better for you.