Ento has already said that he isn't updating until certain changes are made to SV. Most likely, he won't make a version for the beta at all. Please be less pushy in asking someone to do something for you. If you need XNB Loader, use SV 1.2 until an update is made.
On top of what 13akoors said, XnbLoader is not recommended for modding your game if you can use Content Patcher or a similar modern mod. Xnb modding is being phased out due to it being a heavy-handed approach. XnbLoader will (eventually) be updated for 1.3, but I can already tell you that it is unlikely that I will continue updating it once 1.4 (the More Languages Update) is released.
Oh dear... it's gonna be a shame if this mod won't keep receiving updates after 1.3. I understand the reasoning, of course, but still - I have all of my custom sprites set up to work with this specifically cos it's so much easier than fiddling with code thru Content Patcher. I'm not a programmer and the prospect looks terrifying Oh well, at least I'm waiting until the beta is over before I jump back into the game so hopefully we'll get an update to this mod by then. Fingers crossed
Content Patcher really doesn't require any programming. It requires a bit more from you than XNBLoader, but it also allows you to do even more. Even ignoring the ability to allow all XNB mods to be treated like a SMAPI mod for purposes of bug reporting and updates, it also lets you add to specific in-game files rather than overwriting them, which (in theory) means that no Content Patcher mods should overwrite files used in another mod. XNBLoader was the mod that made overwriting base game files obsolete. Content Patcher makes mod conflicts obsolete (That said, 2 Content Patcher mods that do the same thing will obviously still conflict. But 2 mods can now both add to the same file without issue, or add and overwrite at the same time) I would suggest messaging Pathoschild for resources on using Content Patcher if you're worried about it. He can direct you to specific resources on using the mod, and can give guidance as necessary and his time allows. I know this looks like a sad turn of events, but think of it more as the modding community growing and improving its tools to allow for even more things in the future
XNB Loader 1.11.1 is now available! (For Stardew Valley 1.3.30+ only.) Release notes: Updated for Stardew Valley 1.3. Fixed Linux/Mac compatibility. Removed custom update checks; replaced by standard SMAPI update alerts. Refactored internally. Notice: XNB Loader is now deprecated. It's no longer in development and probably won't be updated past 1.3. Consider migrating to Content Patcher instead. Many authors have already migrated their mods, and there's a list of unofficial conversions for those who haven't. (It's only on Nexus since I don't have access to update the Chucklefish mod page, but Entoarox is welcome to upload it here too.)
I noticed, when I installed the XNB Loader 1.11.1, it did not create a ModContent Folder. Should I put one in manually? I was only putting it on for those few mods I had that haven't been updated to CP, there are maybe 2 of them (Better Rain and Blue Galaxy Sword - I would do CP versions if I even began to understand Modding for this game and had the original author's permission), so it's not a huge deal, but I thought you might want to know it wasn't creating the ModContent Folder, and I'm running Windows 10 Home. EDIT: A bit more poking around revealed it wasn't loading Entoarox Framework, and therefore not initializing the Mod properly. The link to update Entoarox Fragment on the Mod Compatibility page wasn't immediately obvious that I wasn't using the right version (2.4.0 was wrong, 2.4.1 was right and worked), and I incidentally realized my versions of Extended Minecart and Content Patcher were likewise Out of Date. Updating Content Patcher fixed my ability to load about 20 CP mods I had installed. Updating these three mods has fixed quite a few problems. Thanks for keeping it all up to date. And the ModContent Folder was created on initialization as it was supposed to be, and the two mods listed above are my last remaining holdout XNB Mods. Please keep up the good work keeping everything up to date, and you might want to note which version is the most current version on the Mod Updating Page to prevent confusion in the future.
@Galliard Versions are a bit messy during the transition, but I updated all the Entoarox mods so they only have the latest version now. You should get update alerts automatically in the SMAPI console for those.