Ok thanks - that’s helpful. We’re working on getting more sentences added, especially for HSK 4/5/6.
It looks like for HSK 4, Tatoeba doesn’t yet have sentences for
包子, 打印, 打折, 打针, 登机牌, 积累, 京剧, 烤鸭, 矿泉水, 垃圾桶, 凉快, 马虎, 填空, 小吃, 性别, 预习, 占线
HSK 5
岸, 报到, 本科, 本领, 比例, 鞭炮, 标点, 步骤, 操场, 差距, 成分, 诚恳, 吃亏, 尺子, 初级, 闯, 打工, 单元, 发票, 分布, 分配, 辅导, 概括, 干活儿, 格外, 个别, 公布, 乖, 怪不得, 官, 归纳, 国庆节, 海关, 合影, 何必, 何况, 后背, 糊涂, 华裔, 急诊, 纪律, 系领带, 夹子, 嘉宾, 坚决, 健身, 阶段, 结合, 结账, 近代, 经商, 桔子, 军事, 均匀, 拦, 朗读, 劳驾, 厘米, 连忙, 陆续, 名牌, 名胜古迹, 模仿, 目录, 内部, 嫩, 培训, 赔偿, 配合, 盆, 拼音, 频道, 青, 群, 人事, 弱, 色彩, 商务, 生动, 省略, 使劲儿, 梳子, 撕, 随身, 桃, 特征, 提纲, 体会, 体现, 调皮, 透明, 推广, 委屈, 武术, 勿, 吸取, 夏令营, 鲜艳, 斜, 幸亏, 性质, 休闲, 虚心, 叙述, 学历, 要不, 一律, 乙, 油炸, 运用, 阵, 振动, 证件, 执照, 转告, 紫, 自觉
and HSK 6 is especially poorly represented with 1040 words missing of a possible 2500.
So! We’ll work on getting the existing HSK 4/5/6 collections updated first, and we’ll see if we can’t get sentences added for the words currently missing on Tatoeba. If you’d like to help contribute to Tatoeba for these words that would of course be helpful. Will post more updates here. Work in progress! 
Edit: An additional note - splitting Chinese sentences into words can be a bit tricky/inaccurate sometimes, so it may be that a word above is “missing” because we haven’t identified it in a given sentence accurately, but we’re using the most accurate method we’re aware of at the moment.