The web galleries in Lightroom CC unfortunately are not a good option to send files to a client. It will always render the file again to new files, even if your originals are sRGB jpegs. Lightroom treats your jpeg files just like it treats raw originals and it will create new files for download. If you want to send files to a client and have absolute control use a file sharing service. Adobe provides one with the creative cloud drive service, so you might be able to use that. This is available from the creative cloud app in the item with the three vertical dots (creative cloud files). Create a folder there and save your jpegs there. Then control click (or right click) on the folder and open the folder on the web and share it from there with your client using the tiny icon of a person with a plus on it. There are many other services to do this such as dropbox, box.com, msn, etc. etc.