Current Firmware / Custom ROM for Odys Uno X10?

Good evening,

If this is the wrong forum for this question, please just move to the right place -bin new !!

Equal first, am not a computer expert, but a pure user who progresses à la Recipe mostly with goal-oriented data and achieved his goal.

The background:
Have a Odys Uno X10 and am so far with the operating system 4.2.2 Jelly Bean as far gotten along; read mail, office applications, Googling, my practice software with TeamViewer control. do the bookkeeping. 
But since I have to use a device so professionally that at least Android 4.4 requires (AirSmart, to be exact), and I do not want the same to buy a new tablet, I decided to try the old Odys Uno X10 to miss a new operating system , Here's the technical details:
The installed Android Version: 4.2.2
Kernel Version: 3.0.50
Build Number: AML MXS_ANDROID4.2.2_ODYS_UNO_X10_V1.0.4_20140331

Here's what I have already done after some Internet research:
- Kingo Root of Chip.de downloaded, installed on the PC and the tablet rooted it.
- Root access to the Root Checker Basic confirmed and checked.
- Superuser Elite installed.
- ROM Manager installed.
- Since recovery in ROM Manager does not support the device, the Official TWRP app loaded.
- Data backed up.

==> Now the real problem is: Where can I find a usable custom ROM?
According to Internet research, is the last version that could be loaden, 1.0.4 (installed?)
recommended in many forums and on chip and in several Youtube tutorials Cyanogenmod versions no longer there, or I do not find this
In LineageOS I find the device or not at all Odys
With Dirty Unicorns the list of suitable equipment is missing at all
Slimroms not also lists Odys.
=> perhaps someone knows a build version that I could use? If so, where can I get this?

Thank you already for your patience and effort!