Sound effect translation
Translating sound effects can be difficult. In case you find yourself having difficulty translating a sound: just trust your instincts provided by comics in your culture and use the spelling that sounds most right to you. Sometime it could be as simple as trying out the sound out loud with your mouth, and then using the phonology of your language. The result is anyway often very subjective and will be only here to show to the reader that a sound is important for the story and/or help their imagination to complete the missing soundtrack. Be creative!
Common issues editing them in Inkscape
I had to find a compromise between having artistic onomatopoeia and something possible to edit. You can always start by editing text as you would do by double clicking on it and type your translation. Many effect will works fine this way.
Unfortunately, some part of the text effects will be deleted by the editing and not look as it was on the source:
So here is a list of method you can apply to recover the effects:
Resize letters one by one:
A big classic (and the case in the visual above "common issue") is when the onomatopoeia has different size for each letters. It convey the volume of the sound: fading, or increasing. This type of data are generally lost while editing; but can be edited back by selecting each letter and giving them a different size (eg. 200px, 180px, 160px, etc...).
Rotation of individual letters can be very useful to produce cascading effects. I often apply the same value to all the letters of a soundFX and shear the whole box or put the text on a path. Unfortunately, here also the rotation gets crunched at editing the text. Values can be positive (clockwise) or negative (anti-clockwise).
Horizontal (in-between character) spacing:
To space the letter or to overlap them. I often use it to overlap them a bit to give a bit more packed aspect to the full sound; making the letter touch each other.
Vertical (baseline) spacing:
More rarely used; each letters can have various high compare to the baseline of the text. It's nice to create some waves of high in the text and simulate some modulation of pitch of sound. Some values can be negatives (under the baseline) and some positive (over the baseline).
Tweak the aspect (SVG Filters):
Almost all the sounds effect you'll meet in Pepper&Carrot uses SVG filters. These filters are stack of effects that allows to add multiple outlines, variations of stroke, shadows and more. If you want to tweak the effect and access to this stack of settings, select the text and open the dialog
Filters > Filter Editor. Then you'll have sliders to edit all the thickness and colors of the effect. It's rarely required to translate the webcomic; but I can imagine the situation where the effect is too strong and affect the glyph of a language. In this case, calming the turbulance, the width, or the drop shadow of an effect might be useful.
Advanced: XML editing
To finish, the ultimate method when you want a 1:1 copy of the effect, is to edit the data of the SVG file directly. This method is advanced because it requires to edit the SVG file with a text editor and locate in the jungle of XML tags where the letter of the effect are printed in it. You might need to search (Ctrl+F) for it. But once you found them (often encapsuled in their own XML tags), you can easily replace only the text with your translation, save the text and reopen with Inkscape to see the rendering: the effect should be totally preserved.