It is easy and very flexible. There are many ways to avoid such bad situation. I just take 2 usual solutions.
1st, use other words to instead. Different from English, Chinese character/hanzi have lots of similar words to instead. For example, if we say agree with your idea , we can say : 对，好，善，理当如此，甚妥，当然，妙，可以，有道理，etc. When we make speech and forget some word, we will replace it with other words at once. Same as writing.
2nd, If must write specific Hanzi, we can guess its structure. most of Chinese Hanzi use, left /right, up /down structure. Usually left & down means its attribution and type. Right and up means it’d sound/ pronunciation. like 坊, if we forget its writing, we can guess its meaning and attrition first. It is about house, so the Hanzi left must be and 土/land, and its sound fang, so usually must be 方。This way keep 95% accuracy, except our 1000s basic Hanzi.
There are also other ways to instead like Pinyin, draw a circle, Baidu search, Sogou Pinyin input. It is easy.