I’ve shot a sunset tjmelapse. I used lightroom and letimelapse to even out the exposures. When i view the preview in lrtimelapse it looks perfect and smooth, but when exported the video has harsh transitions of exposure in it. Please help me how to solve this? More keyframes? I used 10 keyframes now

If you are using matching versions of LR Classic and Adobe DNG Converter, the develop engine for the Visual Previews and the Export will be the same. That means, if the previews play smooth, the export will look exactly the same if you did the workflow right.
I could imagine that something with the workflow is wrong. Either you are working on different folder in LRT and LR or you didn't really read all the metadata into Lightroom (Make sure to be in Grid view, have the filter set to "Full Sequence" and then select all images. Now do "Metadata / Read Metadata from files". Then reexport and rerender.

I did a fresh install yesterday. I work from the same folder in lrt and lr and do exactly as you described. And still it gives me some smooth but on 6 place in the timelapse a hard transition from exposure.

Could you please start over the editing via Metadata/Initialize in LRTimelapse and removing the sequence from Lightroom.
Please follow the instructions on https://lrtimelapse.com/workflow/ (Visual Workflow). Also make sure to deflicker with a proper reference area (see deflicker tutorial on https://lrtimelapse.com/tutorial/ ). Do a couple of refine steps until the pink curve is smooth.
If you still experience issues, please upload the result somewhere and share the link.