Control blinds including custom scripts with Alexa

Dear community,

I’m controlling my blinds using rollershutter commands and added two custom scripts to automatically put them into vent or intermediate mode (“aublenden” or “zublenden”).
It was easy to implement these buttons in sitemap - rollershutter commands with up/stop/down and the two buttons “aufblenden” and “zublenden”. Both buttons send a decimal state to a multiswitch, which executes the script defined in rules.

Some days ago I bought an amazon echo dot and would like to control them with Alexa. It basically works to control the blinds using percentage and stop commands, but it’s hard to run the script.
It is possible to control the blinds as “switching”-items, but then you have to say the work “on” after every command. And a dedicated switch-item is required for every function.

After some research I was able to configure a lightning-item and execute commands based on the percentage spoken: 2 percent = go up, 3 percent = go down, 4 percent = close, 5 percent = open.
However, percentage are not very comfortable and also the german numbers 2 and 3 can be misinterpreted if not spoken clear and load.

I though to change the lightning config to “dimmer” and introduce some new, special colors for “aufblenden” and “zublenden”, but I’m not sure if this will work.

Does anybody know how to configure the items and rules to achieve this? Is there a way to introduce a “custom command” to openhab which can be used with Alexa?
My goal is to have on single item for every blind or group of blinds, which will have 5 german commands: rauf, stop, runter, aufblenden and zublenden.

Many thanks.